ECON Son c ak we Tony a CORNELL | UNIVERSITY | LIBRARY a University Library SD 435.R31 of thee ‘ii 104241 | aN i, a ith ie WR i a BANT 1 nt na ie Quercus alba (white oak): cross section through one entire growth ring and portions of two others. Note large pores in early wood filled with tyloses and abruptly diminishing in size toward late wood. Small pores thin-walled and in fan-like groups. Note ‘‘dipping in” of the outline of the growth ring where it crosses the large ray at the left. x 35. Identification OF THE Economic Woods of the United States Including a discussion of the Structural and Physical Properties of Wood BY Samuel J. Record, M.A., M.F. Assistant Professor of Forest Products, Yale University FIRST EDITION FIRST THOUSAND NEW YORK JOHN WILEY & SONS Lonpon: CHAPMAN & HALL, Limrrep 1912 CopyricutT 1912 By SamueL J. Recorp PRESS OF THE PUBLISHERS PRINTING COMPANY, NEW YORK, U.S. A. CONTENTS INTRODUCTION : : : 4 3 PART I STRUCTURAL AND PuysicaL PRorpeRTIES OF Woop: General Pith Bark Primary wood Cambium Secondary wood Vessels Tracheids Wood fibres Wood parenchyma Rays Resin ducts Pits Tyloses : ; Pith flecks or medullary spots Bars of Sanio Tier-like arrangement of elements Growth rings Heartwood and sapwood Grain and texture Knots Density and weight Water content of wood iii 11 12 12 14 16 18 21 23 29 31 35 36 38 39 40 44 46 48 49 52 lv CONTENTS Shrinkage, warping, and checking . Hygroscopicity Penetrability Conductivity Resonance Color Gloss or lustre Scent or odor Taste List or GENERAL CLASSIFICATIONS OF Woop PusiicaTions DEALING WITH THE CHARACTERISTICS OF Woop PusuicaTions DEALING WITH THE USES oF AMERICAN Woons, PART II . Key To THE Economic Woops or THE UNITED StTaTES REFERENCES , : F x ‘ ‘i é ‘5 . INDEX . - = 3 3 5 $ ‘ é q 5 PAGE 56 59 60 62 62 64 66 67 69 69 71 76 78 105 . - 111 ILLUSTRATIONS PLATE Cross section of Quercus alba (white oak) Frontispiece PLATES Map of the United States showing natural forest regions I Photomicrographs of wood sections , ‘ II-VI TEXT ILLUSTRATIONS Fic. PAGE 1. Cross section of stem of Quercus prinus (chestnut oak) 6 2. Typical wood cells 19 8. Radial sections of heterogeneous rays 24 4. Radial section of ray of Pinus strobus (white pine) 25 5. Radial section of ray of Pinus edulis (pinon pine) 26 6. Radial section of ray of Pinus resinosa (red pine) ‘ 27 7. Radial section of ray of Pinus palustris (longleaf pine) 28 8. Cross section through portions of two growth rings of Pinus ponderosa (western yellow pine) 30 9. Tangential section of fusiform ray of Pinus ponderosa (western yellow pine) 31 10. Cross section of a wound area of Tsuga canadensis (eastern hemlock) 32 11. Schematic representation of pits 33 12. Bars of Sanio in Pinus murrayana (lodgepole pine) 38 13. Cross section through three entire growth rings of Quercus macrocarpa (bur oak) 42 14. Cross section through one entire growth ring and parts of two others of Quercus macrocarpa (bur oak) 42 15. Effects of shrinkage ‘ é ; ‘ ‘ ' 57 TABLES ° No. “3 PAGE I. Length of tracheids in coniferous woods : ; ‘ . 17 II. Length of wood fibres in dicotyledonous woods ‘ : ‘ . 20 III. One hundred and fifty trees of the United States arranged in the order of the average specific gravity of their dry woods . . 50 IV. Shrinkage of wood along different dimensions i 3 ‘ . 57 vii INTRODUCTION As the available supply of the standard kinds of timber has decreased, woods have appeared on the market which formerly were considered worthless. In some instances the new woods are sold under their own names, but usually they are employed as substitutes for more expensive kinds, or sold in indiscriminate mixture. It thus becomes a matter of great importance that foresters, timber-inspectors, and wood-users be able to distinguish the woods with which they deal. The number of such woods is so large, and their resemblance often so close, that one can no longer depend upon distinguishing them through mere familiarity with their general appearance. To identify woods it is necessary to have a knowledge of the fundamental differences in their structure upon which the points of distinction are based. The literature bearing directly upon this subject is very limited, and such information as exists is for the most part dis- tributed throughout a considerable number of publications and not readily available. Teachers and students of wood technology are seriously handicapped by the lack of suitable text-books or manuals. It is in an attempt to supply in small part this defi- ciency that the writer has prepared for publication a portion of the material given in one of his courses in Forest Products at the Yale Forest School. While it is designed primarily as a manual for forestry students, it is hoped that it will also aid others in the study and identification of wood. Part I deals briefly with the more important structural and physical properties of wood. The structural properties are based upon the character and arrangement of the wood elements. Under this head are considered: (a) the external form of the tree in its various parts; (6) the anatomy of the wood; (c) abnormal developments or formations; (d) relation of these properties to the usefulness of wood; and (e) their importance in classification. The physical: properties are based upon the molecular composition of the wood elements. Under this head attention is given to (a) the properties manifest to unaided, senses, viz., color, gloss, 1 2 INTRODUCTION odor, taste, and resonance; (b) those determined by measurement, viz., density, weight, water content, shrinkage, swelling, warping, and hygroscopicity; (c) relation of these properties to the use- fulness of wood; and (d) their employment to some extent as aids to identification. In Part II attempt is made to use the details of Part I in the construction of an artificial classification of the economic woods of the United States. Unimportant species have in some cases been included where it was felt that their presence would not lead to confusion. This classification has been prepared with two objects in view: (1) for use in practice as a key for the identifica- tion of unknown specimens; (2) for use in the laboratory as a basis for the comparative study of known specimens. As far as considered practicable, the distinctions in the key are based on macroscopic features, those readily visible to the unaided eye or with the aid of a simple lens magnifying 10 to 15 diameters. Owing to the great variation of wood it is usually unwise to rely upon single diagnostic features, and for this reason the descriptions have been extended to embrace all or most of the important characters so far recognized. This method also permits ready rearrangement of the key or the fitting into it of additional woods. . In the woods of many genera the structural variations appar- ently are not sufficiently distinct and constant to assure specific identification. Good examples of this are afforded by the woods of Pinus, Quercus, Hicoria, and Populus, where it is usually difficult and very often impossible to do more than separate them into groups. Accurate knowledge of the botanical and com- mercial range of each species will often serve as a basis for further subdivision of a group in which other distinctions are apparently wanting. In preparing a specimen for careful examination either with or without a lens it is highly desirable that a very smoothly cut surface be obtained. If the knife used is not sharp, the cut surface will be rough and the details of structure obscured. Cross sections are, as a rule, the most valuable for comparative study, and in making them it is very important that the plane of section be as nearly as possible at right angles to the vertical axis of the specimen. A compound microscope is necessary for the study of the minute anatomy of wood. Sections for immediate observation INTRODUCTION 3 may be cut free-hand with a sharp pocket-knife or razor and mounted in water. To avoid air bubbles in the sections small pieces of the specimens should be boiled prior to sectioning. It is not important that such sections be of uniform thickness, since a thin edge will usually exhibit the essential details. Much better results can be obtained by the use of a microtome. Penhallow recommends a table microtome and a plane blade mounted in a heavy wooden handle of such a form as to provide a perfectly firm grip. For fine work, however, a sliding microtome specially constructed for sectioning wood is best. Success depends largely upon the sharpness of the knife and the rigidity of the apparatus. Considerable care should be exercised in the selection of material for sectioning. Small blocks of about a quarter-inch cube should be cut from green material, or from the interior of dry pieces. The faces of the blocks should represent sections which are as nearly cross, radial, and tangential as possible. Blocks of the lighter woods can be softened sufficiently by boiling them in water until thoroughly saturated. The process may be hastened by interrupting the boiling by additions of cold water. In the case of the harder woods, however, it is a good plan to place the small blocks, after boiling, in a solution of hydrofluoric acid for a period varying from ten days to three weeks, the strength of solution and the duration of immersion depending upon the hardness of the wood. After removal from the acid the blocks should be thoroughly washed and then placed for several days in glycerine, after which they are ready for sectioning. The sections may either be mounted unstained in glycerine or stained in the usual way and mounted in balsam. For ordinary work unstained glycerine-mounts afford the most satisfactory results, since the natural colors are preserved. (For more detail, see references below.) References Baitey, I. W.: Microtechnique for Woody Structures, Bot. Gaz., Vol. XLIX, Jan. 1910, pp. 57-58. Prowman, A. B.: The Celloiden Method with Hard Tissues, Bot. Gaz., Vol. XXXVII, June 1904, pp. 456-461. PrenHALLow, D. P.: North American Gymnosperms, Boston, 1907, pp. 16-23. Benepict, H. M.: An Imbedding Medium for Brittle or Woody Tissues, Bot. Gaz., Vol. ‘LIT, Sept. 1911, p. 232. Tuompson, R. B.: A Modification of a Jung-Thoma Sliding Microtome for Cutting Wood, Bot. Gaz., Vol. L, Aug. 1910, pp. 148-149. 4 INTRODUCTION The best idea of the form and size of the individual cells is gained from studying macerated material. This is readily obtained by placing small pieces of wood in a test-tube together with a number of crystals of potassium: chlorate, and adding enough nitric acid to cover them well. After the wood has turned white the solution should then be poured off and the material washed thoroughly in water. This action may be hastened by warming. ‘It is then easy to remove a small portion of the mass to a slide where it can be dissected with a couple of needles and studied under the microscope. The writer desires to acknowledge his indebtedness to Prof. James W. Toumey for much of the data upon which this work is based; to Mr. Clayton D. Mell for many helpful suggestions and criticisms; and to Mr. Charles J. Heller for the loan of a set of wood sections from which the photo-micrographs were made by the writer at the Forest Products Laboratory, Madison, Wis- consin. PART I STRUCTURAL AND PHYSICAL PROPERTIES OF WOOD GENERAL Wood of a timber-producing tree may be considered under three general heads, viz., root, stem, and branch. The relative proportion of the three classes of wood in a tree depends on the species, the age, and the environmental conditions of growth. The woody portion of stem and branch has, within certain limits, the same structure. Branches are of less technical value because of their irregular shape and small dimensions. The latter is due to the fact that the number and thickness of the layers of growth are less and the wood elements smaller than in the bole. Wood of roots always differs somewhat from that of the stem in form, structure, and distribution of the elements; the growth rings are narrower, the elements have wider lumina, and the wood is as a rule lighter, softer, and more porous. Roots, with occasional exceptions, are a very subordinate source of wood in America. Stem wood, on account of its more desirable dimensions and shape and its greater uniformity, is of the greatest utility and value. The form and character of the stem are of greater impor- tance than the relative volume; with few exceptions the more nearly straight and cylindrical and the freer from limbs, knots, and _ defects, the greater are its technical properties and value. . These properties are largely determined by the age of the tree and the inherent characteristics of the species, though affected by environment. Straightness and clearness are materially influenced by density of stand. A woody stem, branch, or root is composed of three unlike parts (Fig. 1). Through the central portion runs a narrow cylinder of soft tissue, the pith. On the outside is bark. Between these two and making up the bulk of the structure is the wood or xylem. The wood, particularly in old sections, usually shows a central 5 6 ECONOMIC WOODS OF THE UNITED STATES colored portion, the heartwood, and a nearly colorless outer border, the sapwood. In fresh-cut green sections the sapwood is further differentiated by its greater moisture content. Indigenous arborescent plants are readily separable into two j G if hie i he As Ps Wy yy UT) py if ij hy TH Ure Ly ry 5 iy WY, a . mn AO HUNT aS mo PA . KORN Ra hi A a Fic. 1.—Cross section of stem of Quercus prinus (chestnut oak); 6, bark showing outer and inner portions; s. w., sapwood: the darker inner portion is heartwood; u.+., annual or growth ring; p.r., (pith) ray, a large number of which can be seen crossing the growth rings at right angles. Note season checks. Natural size. (From Bul. 102, U. S. Forest Service.) great natural classes: I, Gymnosperms, and IJ, Angiosperms. Class I is further divided into two unequal groups: Conifere (13 genera), and see ie (2 genera). Class II embraces (according to oe ECONOMIC WOODS OF THE UNITED STATES 7 Sargent’s “Manual of the Trees of North America’), Mono- cotyledons (2 families and 8 genera), and Dicotyledons (57 fam- ilies and 149 genera). The Monocotyledons are of comparatively slight importance as sources of wood, and for that reason, as well as on account of their peculiar structure,* are omitted from the general discussion of wood and from the key. The woods of the Gymnosperms are commonly referred to as “coniferous woods,” ‘soft woods,” and ‘“needle-leaved woods.” These terms are inexact since (1) the Taxacew do not bear cones; (2) many of the so-called ‘soft woods” (e.g., Pinus palustris, Pseudotsuga, Taxus) are harder than many of the so-called “hard woods” (e.g., Populus, Salix, Hisculus, he and (3) the con- XX lia) ; trast in the leaves is by He Means Always Bee ent as the terms “needle” and ‘broad’ would indicate. Common usage, how- ever, has given these names sufficient definiteness for ordinary: purposes, though they should be avoided where scientific exact- ness is desired. PITH The central portion of the young shoot, branch, and root is composed of loosely aggregated, mostly thin-walled, isodiametric, parenchymatous cells—the pith. It is usually of small diameter, does not increase in size after the first year, in fact, may even in some instances be compressed, and appears to be of only temporary utility to the tree. In some cases, according to Gris (loc. cit.), the cells remain active for several years, and alternately store and give up products of assimilation, especially starch and tannin, according to the periods of vegetation. In such instances the walls of the active cells are thickened and densely pitted. The pith in woody stems of Gymnosperms is fairly uniform in shape, size, color, and structure; in Dicotyledons there is great variation. As to ous in eet section, it is star-shaped in a et a . we Quereous, triangular, in Fagus, fi ape A Busi. ovoid in Tilia,/ Fraxinus, and Aéer; circular in Sug ans, OUlmus, and Cornus. 4 In Juglans the color is black; in Gy agus, it is red; in many others it is brown or gray. In Rhus, ucus, and Ailanthus the tops Lhe, tL Are rf star *In adult stems of Monocotyledons the fibro-vascular bundles are scat- tered throughout the central cylinder instead of being disposed in a circle, as in the Dicotyledons. The bundles are closed and the tracheary tissue surrounds the phloem. 8 ECONOMIC WOODS OF THE UNITED STATES pith is comparatively large and conspicuous, often deeply colored. In Magnolia, Liriodendron, Nyssa, Apohaes and Anena paste is often a more or ‘fesédistinet sept. Of the Gontintous pith by plates of stone cells, while in Juglang,there is decided septation but the diaphragms are not soles and the pith is not con- tinuous between the disks. On account of these and other pecul- iarities the pith when present in a specimen of wood is frequently an aid to identification. . References DeBary, A.: Comparative Anatomy, Oxford, 1884, pp. 402-403; 533-534. Foxwortuy, J. W.: Discoid Pith in Woody Plants, Proc. Indiana Academy of Science for 1903, Indianapolis, 1904, pp. 191-194. SoLeREDER, Hans: Systematic Anatomy of the Dicotyledons, Oxford, 1908, pp. 133-134. Gris, A.: Sur la Moelle des Plantes Ligneuses, Amer. Sci. Nat., Sér. 5, Tome XIV, 1872. BARK Bark is the name commonly applied to that portion of a stem lying outside the cambium layer. Used in this broad sense, it is customary to distinguish an outer (dry) portion and an inner (living) portion. The structure of bark is highly complex and widely variable. When shoots are first formed they are covered by a very thin layer of tissue, the epidermis. Beneath this is the primary cortex and the pericycle. The latter is commonly composed of two kinds of tissues, thin-walled parenchyma and bast-fibres. The bast- fibres may occur in isolated groups or form a continuous band around the stem. When in groups they are often closely associated with, but not really part of, the phloem of the vascular bundles. Bast-fibres are attenuated sclerenchymatous elements, with sharp ends simple or branched. Their function is to give strength to the stem and to protect the delicate tissues of the phloem. It is to them that many barks owe their great toughness and pliability. Phloem, which is the outer portion of a vascular bundle, is in typical cases composed of sieve tubes, companion cells, and phloem parenchyma. In structure sieve tubes resemble vessels, but their walls are mostly delicate, non-lignified, colorless, cellulose mem- ECONOMIC WOODS OF THE UNITED STATES 9 branes. Between the ends of the sieve-tube segments (and some- times between adjacent side walls as well) are thin plates dotted with pits, resembling a sieve. The pit membranes are finally absorbed, allowing free communication from one cell to another. Unlike vessels, the segments of the sieve tubes remain alive for a year or more, though they lose their nuclei. This unusual phe- nomenon may be due to some influence of the companion-cells which are always so closely associated. The function of the sieve tubes is the vertical (especially downward) distribution of elab- orated food materials. After the first year the cells usually be- come crushed by the pressure of the surrounding tissues, their places being taken by new cells generated by the cambium. In addition to the structure just mentioned, many other elements and structures may enter the composition of the bark. Among these may be mentioned resin ducts, latex tubes, stone cells, crystals, mucilage sacs, and tannin sacs. Bast rays are also present, being continuous with the rays of the xylem. They increase in width uniformly and gradually as they recede from the cambium. In practically all cases of growth in thickness the epidermis is destroyed at an early period and is replaced by cork. Cork is suberised tissue formed by a special meristem called cork cambium or phellogen, which originates in the epidermis or in the cells just beneath the epidermis. All parenchymatous cells, however, wherever located, appear to possess the ability to form cork. Wound surfaces are closed and healed by it, and diseased and dead parts are isolated from those in living condition. The formation of cork cambium in the bark usually occurs during the first year’s growth of the stem. As a result of its activity a layer of cork cells is generated on the outside, and fre- quently a layer of thin-walled parenchyma cells—the phelloderm— on the inside. Collectively these new tissues, including the cork cambium, are called the periderm. The effect of the development of cork is to cut off from the interior mass of tissue portions of the cortex, which dry up and are eventually thrown off as outer bark., 4/:'‘ ae This action may occur only once, as in Fagus and Carpinus, but ox: usually is repeated, and successively deeper layers of the cortex — and eventually of the pericycle and phloem are cut off. In some species the successive formations of cork extend more or less uniformly around the stem, cutting off in each case an annular layer of cortex—sometimes called ring bark. In other species the successive internal layers are very irregular, and cut vom 10 ECONOMIC WOODS OF THE UNITED STATES off scale-like portions of the cortex—scale-bark. The results are subject to very wide variation. <__In,Platanus and ‘Taxus the outer bark is shed annually in Tie ters of comparatively large, irregular, thin flakes which, fallin away, leave the surface smooth. In species of Betula thin, exfoli- ating layers are produced, marked with horizontal lines of lenticels. In many species of Pinus, the outer bark of mature trees is made ~up of small, irregular scales in very intricate pattern. In Hicoriaé ovata and H. laciniosa the outer bark peels off in long, flat, reddish- brown strips, while several other species of the same genus have bark that is not flaky. In a great many woody plants the layers of bark persist for many years, and, as the stem increases in size, become more gnd more cracked,and furrowed. Such is the case in Quercus, Robinia, Liriollendrén, etc. In Sequoia, Juniperus, Taxodium, and others of the Cedar group, the bark is character- istically fibrous. These examples are sufficient to indicate the wide variation in the bark and its importance as an aid to the identi- fication of a specimen upon which any portion of bark remains. The bark of many trees is of high techn tei * very great number are used for medicinal purposes. T’suga and species of Quercus possess barks which furnish a large proportion of our tannin supply, upon which the leather industry is dependent. Some barks contain coloring principles; others (e.g., Hicoria ovata) are highly valuable for fuel. Birch bark was formerly used for canoes. The inner barks of some woods (e.g., Tilia) are sometimes used in manufacturing fibre cloth. The highly-developed corky layers of Quercus suber furnish the cork of commerce. References Srevens, W. C.: Plant Anatomy, Philadelphia, 1907, pp. 37-39; 56-58; 72-82. DeBary, A.: Comparative Anatomy, pp. 108-114; 519-566. Sacus, Juurus: Text-Book of Botany, Oxford, 1875, pp. 90-92. Grecory, E. L.: Elements of Plant Anatomy, Boston, 1895, pp. 133-142. Henxet, Auice: American Medicinal Barks, Bul. 139, U. 8. Bu. Plant Industry, 1909, p. 59. Hitt, ArTHuR W.: Sieve-Tubes of Gymnosperms, Annals of Botany, Vol. XV, Dec. 1901. : Notes on the Histology of the Sieve-tubes of Certain Angiosperms, Annals of Botany, Vol. XVII, Jan. 1903, pp. 265-267. Mog ier, JosepH: Anatomie der Baumrinden; Vergleichende Studien, Ber- lin, 1882, p. 447. ECONOMIC WOODS OF THE UNITED STATES 11 PRIMARY WOOD At the growing apex of a stem is an undifferentiated tissue composed of very thin-walled cells essentially all alike. This tissue is known as the primordial meristem. Below the apex the primordial meristem becomes differentiated into three distinct parts, viz., (1) the protoderm at the outside, (2) the procambium strands, and (3) the fundamental or ground meristem. These three regions or tissues are themselves subject to further differentiation and are called primary meristems. The protoderm changes into the epidermis; the ground meristem into pith, primary rays, pericycle, and primary cortex; the pro- cambium strands into vascular bundles, which are disposed in a circle around the pith and separated from each other by the primary rays. The vascular bundles are composed of three parts, an inner called the xylem, an outer called the phloem, and, separ- ating the two, a thin layer of generative tissue, the cambium. These tissues, being the direct development of the cells of the procambium, are termed primary (primary wood or proto- xylem, and primary phloem or proto-phloem), in contradistinction to the tissues generated by the cambium, which are termed secondary. Primary wood is relatively unimportant, though of scientific interest because of its peculiar structure, which in many ways differs from the other wood of the stem. Thus in Angiosperms, wood fibres are usually wanting and tracheids are not common in the primary wood, while in the secondary wood fibres are always present and tracheids commonly so. In Gymnosperms the vascular elements of the primary wood are indeterminate in length, marked with spirals and for the most part devoid of pits in their walls, while the corresponding elements in the secondary wood are of determinate length, rarely marked with spirals and always pitted. References Stevens, Wituiam C.: Plant Anatomy, pp. 25-45. PENHALLOW, D. P.: North American Gymnosperms, pp. 38, 40. DrBary, A.: Comparative Anatomy, p. 321. Sacus, J.: Text-Book of Botany, p. 574. 12 ECONOMIC WOODS OF THE UNITED STATES CAMBIUM As previously stated, that portion of a pro-cambium strand which remains capable of division and generation is known as fascicular (2.e., bundle) cambium, since it produces on the inner side wood or xylem, and on the outer phloem—collectively a fibro- vascular bundle. The cambia of the several bundles are later united into a continuous sheath, and the portion between the original bundles is termed the inter-fascicular cambium. The cambial layer sheathes the entire woody cylinder from root to branch and separates it from the cortex or bark. It is composed of a thin layer of delicate, thin-walled, vertically elongated cells filled with protoplasm and plant food. It is this layer that is torn when bark is stripped from a living tree. During vigorous growth, “when the sap is up,”’ the cells of the cambium are par- ticularly delicate, a fact taken advantage of in peeling poles, logs, and basket-willow rods. The division and development of the cambial cells give rise to (a) a layer of new wood on the outside of that last produced; (b) a layer of new phloem on the inside of that last produced; (c) continuation of the medullary rays of both xylem and phloem; and (d) new cambium. References DeBary, A.: Comparative Anatomy, pp. 454-475. Bainey, I. W.: Relation of Leaf-Trace to Compound Rays in Lower Dicoty- ledons, Annals of Botany, Vol. XXV, No. 97, June 1911. RusneEr, Konrap: Das Hungern des Cambiums und das Aussetzen der Jahrringe, Naturw. Zeitschrift fir Forst- und Landwirtschaft, 8. Jahr- gang, 1910, pp. 212-262. Von Moat, Huco: Ueber die Cambiumschicht des Stammes der Phanero- gamen und ihr Verhdltniss zum Dickenwachsthum desselben, Bot. Zeitung, Vol. XVI, 1858, pp. 183-198. SECONDARY WOOD Tissues formed from cambium are termed secondary. Almost all of the wood of a stem is secondary wood, the small amount of primary wood being wholly negligible from a technological point of view. The principal functions of secondary wood are (a) to provide ECONOMIC WOODS OF THE UNITED STATES 13 mechanical support for the tree; (b) to afford means for the ascent of sap from the roots to the foliage; (c) alternately to store up and to give back products of assimilation, particularly starch. While the elements of secondary wood are subject to wide variation, they may for convenience be referred to three principal types, viz., (1) vascular, (2) fibrous, (3) parenchymatous. Between these groups are transitional and specialized forms whose reference to one or the other of these groups is often purely:arbitrary. The classification may be extended as follows: Vascular elements Fibrous elements True vessels Wood fibres Tracheids Septate wood fibres (wood) tracheids Parenchymatous elements ray tracheids Wood parenchyma Ray parenchyma In the following table are shown side by side the important differences in the distribution of the elements in tvpical secondary wood of Gymnosperms and Dicotyledons. Gymnosperms Dicotyledons True vessels absent. True vessels present. Wood tracheids present and forming | Tracheids present or absent; always bulk of wood. subordinate. Ray tracheids present or absent. Ray tracheids absent. Wood fibres absent. Wood fibres present. Wood parenchyma present (except in | Wood parenchyma present, and very Taxacee), but usually subordinate. often conspicuous. Ray parenchyma present. Ray parenchyma present. From the above it is apparent that the wood of Dicotyledons is more heterogeneous in its nature than that of Gymnosperms, which is composed almost wholly of tracheids and ray parenchyma. References SotzrEeDeR, H.: Anatomy of the Dicotyledons, Vol. II, pp. 1133-1168. DeBary, A.: Comparative Anatomy, pp. 458-500. Boutcer, G. 8.: Wood, London, 1908, pp. 1-54. Stevens, W. C.: Plant Anatomy, pp. 48-56; 72-112. Sacus, J.: Text-Book of Botany, pp. 92-102. ME tt, C. D.: A Confusion of Technical Terms in the Study of Wood Struc- ture, For. Quarterly, Vol. IX, No. 4, 1911, pp. 574-576. : Classification of Woods by Structural Characters, Am. Forestry, Vol. XIV, April 1910, pp. 241-243. 14 ECONOMIC WOODS OF THE UNITED STATES Strong, H.: The Use of Anatomical Characters in the Identification of Wood, Nature, Vol. LXV, No. 1686, 1902, pp. 379-380. Gayer, K.: Schlich’s Manual of Forestry, Vol. V, 1908, pp. 7-19. Mertzcer, K.: Ueber der Konstructionsprinzip des secundéren Holzkérpers, Naturw. Zeitschrift fir Forst- und Landwirtschaft, 6. Jahrgang, 1908, pp. 249-273. Wie.er, A.: Ueber die Beziehung zwischen Wurzel- und Staumholz, Forstw. Jahrbuch, Tharand, Vol. XLI, 1891, pp. 143-171. Hartic, Ropert:*Untersuchungen tiber die Entstehung und die Eigenschaf- ten des Eichenholzes, Forstlich-naturw. Zeitschrift, Vol. III, 1894, pp. 1-13; 49-68; 172-191; 193-203. Hartic, Rosert, AND WEBER, RupoteH: Das Holz der Rothbuche in Ana- tomisch-physiologischer, Chemischer und Forstlicher Richtung, Berlin, 1888, pp. 20-28. Santo, Cart: Vergleichende Untersuchungen tiber die Elementarorgane des Holzkorpers, Botanische Zeitung, Vol. XXI, 1863, pp. 85-128. : Verg. Unt. ti. d. Zusammensetzung des Holzkérpers, [bid., Vol. XXI, 1863, pp. 358-412. Wiesner, Jutius: Die Rohstoffe des Pflanzen Reiches, Vol. II, Leipzig, 1903, pp. 1-35. VESSELS Vessels are indeterminate, tube-like elements present in the wood of all indigenous dicotyledonous plants. In fact the absence of xylem vessels in woody Dicotyledons is a very rare phenomenon which, according to Solereder (loc. cit., p. 1136), has been recorded only in the exotic genera Drimys and Zygogynum of the Mag- noliacee, and Tetracentron and Trochodendron of the Trochoden- dracee. Vessels arise from cambial cells which increase in size and, through the partial or complete absorption of their end-walls at the close of the process of thickening, become continuous in a longitudinal row. There is always a constriction at the place of fusion of the cells, thus plainly demarking the vessel segments (Plate VI, Nos. 3, 4, 6). The walls of contact of the segments of a ves- sel are sometimes (a) horizontal, but more often (6) oblique, and fit together exactly; or, again, they may be (c) oblique with a por- tion of the opposed faces united, the pointed and blind ends extend- ing beyond the division wall, as in Liquid mbar and Quercus. In (a) the perforation from one segment to nother is simple, t.e., with one round opening. In (}) and (c) the perforations are sometimes ECONOMIC WOODS OF THE UNITED STATES 15 simple and sometimes, especially in strongly inclined division walls, scalariform, that is, the opening is crossed with few to many bars in ladder-like arrangement. The bars are usually transverse to the longitudinal axis of the vessel. Both simple and scalari- form perforations may occur side by side in the same wood, but usually one form prevails. These features have considerable diagnostic value. For example, the perforations are simple in Acer, but scalariform in Betula and Cornus; in Aisculus and Tilia they are mostly simple, but in Liriodendron and Magnolia scalari- form. Tultto Other characteristics of the vessels are the markings on their walls. In most cases they are abundantly pitted with bordered pits, except in contact. with parenchymatous cells where the pitting may be either simple or bordered. (See Pits.) It is very « «>.» common for vessels, particularly the small ones, to be marked with 7 spirals on their interior walls (e.g., Acer, Ilex, Tilia, Ostrya, Ais- culus). In Liquidambar only the pointed énds of the vessel seg- ments are marked with spirals. The function of vessels is to facilitate the ascent of water in the stem. Vessels lose their protoplasmic contents by the time their perforations are complete and become filled with air and water, or air alone. When their activity as water-carriers lessens they frequently become plugged with outgrowths from adjoining parenchymatous cells. (See TyLosss.) the h artwood of certain species (e.g., Gymnocladus, Gledit We eum Prosopts) . they become wholly or partly fille gums or renege others, with carbonate of lime. The length of vessels is usually very great, and doubtless often equals that of the whole plant. In width vessels exhibit great variation not only in different species, but also in different portions of the same growth ring. In some woods all of the vessels are small (e.g., Tilia, 4isculus [Plate VI, Fig. 5], Populus, Salix); in others they are mostly large (e.g., Juglans); very often, as in Quercus (Plate II, Figs. 5, 6), they vary from large (0.6 mm.*) and conspicuous to very small (0.1 mm.). Vessels in cross section are called pores, and when this term is employed it will be understood to apply to cross sections exclusively. Pores are usually readily distinguishable from the adjoining elements by their larger size, though it is not always * One millimetre is equal to about one twenty-fifth of an inch. 16 ECONOMIC WOODS OF THE UNITED STATES possible to tell small pores from cross sections of tracheids. In outline pores may be round, elliptical, or angular. The first two cases are the rule where the vessel walls are thick enough to resist the pressure of the surrounding elements. This is the case, for example, in the small pores of the red and live oaks (Plate II, Fig. 6), while in the white oaks (Frontispiece; Plate II, Fig. 5) the walls are thin and the pores angular in outline. Sometimes pores are disposed in rings or zones in the early wood of the growth ring, producing ring-porous woods (Plate III); in other cases they are scattered singly or in groups throughout the ring or arranged in radial or tangential rows, producing diffuse- porous woods (Plate VI). (See GrowrH Rines.) In any case the largest pores are almost invariably in the first formed wood of the season. The distribution, size, form, and arrangement of the pores are characters of great importance in classifying woods. References SotEREDER, H.: Anatomy of the Dicotyledons, Vol. II, p. 1136. Me tt, C. D.: History of the Investigations of Vessels in Wood, Proc. Soc. Am. Foresters, Vol. VI, No. 1, 1911, pp. 78-91. DeBary, A.: Comparative Anatomy, pp. 155-171; 503. Mayr, H.: Schlich’s Manual of Forestry, Vol. V, 1908, pp. 9-10. Sanio, Caru: Bot. Zeitung, Vol. XXI, No. 15, 1863, pp. 121-128. Hartic, R.: Lehrbuch der Anatomie und Physiologie der Pflanzen, Berlin, 1891, pp. 79-93. TRACHEIDS Tracheids are elongated, spindle-shaped, fibre-like elements, determinate in length and characterized by bordered pits in their side-walls. In the wood of Gymnosperms the tracheid is the dominant element, performing the dual function of conducting water and providing mechanical support for the tree. Bordered pits are mostly confined to the radial walls, except in late wood, and are most abundant near the ends of the tracheids and in one or two rows (Fig. 2, D). Seen in cross section, the tracheids are polygonal in outline, arranged in radial rows, and, near the periphery of growth ring, with very appreciable increase in thickness of the wall, reduction of the lumen, and tangential flattening (Fig. 8; Plate II, Figs. 1, 2,4). In afew species, particularly Pseudotsuga, ECONOMIC WOODS OF THE UNITED STATES 17 wh he, Cedar, Taxus, and Tumion, the tracheids are characterized by spiral thickenings on the inner wall. TABLE I LENGTH OF TRACHEIDS IN CONIFEROUS WOODS BOTANICAL NAME sais Masimum alga at Abies balsamea. . ht eee es Pe 3.10 4.20 2.00 “concolor. .... £4744 4.65 6.00 2.75 “grandis. ..... Tietig ct oe) aie ban | aes Chamecyparis lawsoniana /. era 3.60 4.35 2.55 a thyoides <1 2.10 2.80 1.45 Larix occidentalis..... Lae 2.60 3.80 1.75 Libocedrus decurren ee bay, Aa -%} 4.00 4.70 3.00 Picea engelmanni. Yen flaxtay, marc&| 5.70 6.95 3.05 “pubens..... {0-4 ...a4. iti k..... 2.95 3.65 2.50 sifehenis. 9 ‘ te “eee 2.85 3.70 2.30 Fn. wee 5.90 | 7.20 | 4.40 © &. edulis fe : 1.95 2.55 1.50 “‘lambertiana./...« : iG, av, Mii teces 4.45 5.85 2.75 “ jnontieola..,def ee Wate ae 4.40 | 5.45 | 2.75 “ murrayana. ,C ee qh dict Seer 2.65 3.70 1.80 “palustris. 44.045. 44. #4 t: Sede) Sete Roe hoe 5.55 6.70 3.00 «ponderosa. eer oe twee eee 13480) 4.00 2.50 “ resinosa....//A-t4 ¢/ meh Mo. 4.05 4.80 3.20 “« strobus. . bit ee 3.55 4.55 3.20 “ted... ae GPE ebay oes BLO | 8.90) | 2.85 “virginiana... ....,. pO AD et aioe nae 2.75 3.95 1.75 Pseudotsuga taxifolia. oa Pi 2.70 3.30 1.80 Sequoia sempervirens. x 7.00 9.25 4.05 aia 4 - ree 4.80 5.95 3.45 Taxodium distichum. .4c)0.4.0% 4.70 5.80 3.65 Thuya occidentalis. .@/...,! | 2.00 2.40 1.40 « plicata...... RM: DAS 3.85 4.55 3.15 Tsuga canadensis. . aI 4.00 5.05 2.80 “heterophylla. ..’.. ae Toes ee 3.05 3.65 1.75 In certain conifers, particularly Pinus, specialized forms of tracheids of a parenchymatous type are found associated with resin ducts and cysts. They resemble wood-parenchyma cells in form and function, but have bordered pits in their side and end walls. Analogous to them are the ray tracheids found in several genera of conifers. (See Rays.) The tracheids of broadleaf woods (Fig. 2, #) are subordinate 2 18 ECONOMIC WOODS OF THE UNITED STATES elements often entirely wanting. They are much smaller and less uniform in size and shape than in conifers, and are of most common occurrence in the immediate vicinity of vessels. Their ends are often curved, especially when they terminate just above or below aray. The walls are usually comparatively thin and bear numer- ous bordered pits very irregularly distributed. Intermediate forms of tracheids are sometimes found which show distinct transition to the vessels in the detailed structure of their walls and in the occasional presence of perforations at the ends of the cells. References Prenuatitow, D. P.: North American Gymnosperms, pp. 33-58. DeBary, A.: Comparative Anatomy, pp. 164-165. Tuompson, W. P.: On the Origin of Ray Tracheids in the Conifer, Bot. Gazette, Vol. L, 1910, pp. 101-116. Kny, L.: Ein Beitrag zur Entwickelungsgeschichte der ‘‘Tracheiden,” Ber. d. deutschen Bot. Gesellschaft, Vol. IV, 1886, pp. 267-276. Sanrio, Cary: Botanische Zeitung, Vol. XXI, No. 14, 1863, pp. 113-118. WOOD FIBRES Typical wood fibres (Fig. 2, A, B) are slender, spindle-shaped, sharp-pointed cells with thick walls and narrow cavities. They are further characterized by usually oblique and slit-like simple pits, or less frequently by small, indistinctly bordered pits. Wood fibres are not found in Gymnosperms, but are nearly always present in the wood of Dicotyledons. Wood fibres are of two types, septate and ordinary (non- septate). The septate forms are divided by cross-partitions formed after thickening of the walls has begun. They are of limited occurrence and of relatively small importance. They are characteristic of Swiefenia mahagoni and serve as one means of distinguishing the wood from that of certain others closely resembling it. The ordinary forms are very common and are the principal source of strength, hardness, and toughness of broadleaf woods. While their function is largely mechanical, it is probable that they, especially those with bordered pits, play some part, as yet undetermined, in water transportation. Wood fibres exhibit transitional forms from the typical to tracheids on one hand, and to wood-parenchyma fibres on the ECONOMIC WOODS OF THE UNITED STATES 19 other. In structure and arrangement they exhibit variations of considerable taxonomic value. For example, in Ilex the fibres are rather thin-walled and marked with spirals and bordered pits, and closely resembling tracheids except for their greater size. In Liquidambar (Plate VI, Fig. 1) the fibres are mostly square in cross section and in rather definite radial arrangement. In © : SOP © © Ce Ar s:P- 4 A B Cc Fig. 2.—Typical Wood Cells. A, Wood fibre with very narrow lumen; B, wood fibre with larger lumen and showing oblique, slit-like simple pits (s. p.); C, end of wood fibre showing saw edge; C’, end of wood fibre showing forked structure; D, ends of two tracheids from Pinus showing numerous bordered pits (6. p.); EH, Tracheid from Quercus; F, wood-parenchyma fibre, showing individual cells and simple pits (s. p.); G, chambered wood-parenchyma fibres from Juglans, showing crystals of calcium oxalate; H, conjugate parenchyma cells; K, portion of a vessel segment showing simple perforation (p); ZL, portion of a vessel segment showing scalariform perforation (Sc. p.). Greatly enlarged. Baa0€ ae Robinia (Plate III, Fig. 3) and Toxylon they are in rather large, compact masses in the late wood, separated by groups or bands of pores and parenchyma. In any wood in which they occur they are most abundant in the median portion of the growth ring, and material decrease in the width of a ring is usually at their expense. The ends of most wood fibres are smooth and uniformly 20 ECONOMIC WOODS OF THE UNITED STATES tapering, but sometimes they are flattened, or forked, or with a saw edge (Fig. 2, C, C’), adding to the toughness of the wood. Fibres usually run parallel to one another, but in some woods they exhibit a decided interweaving which produces an irregularly grained wood very difficult to split. TABLE II Lrenetsa oF Woop Fisres in DicotyLeponous Woops BorTaNicAL NAME averace Seren sr Aer TUDTUM gai cciniiny saiinw eg diomaneamadns ess .75 1.00 50 BEtU a MOTE a 1 wsisne awe wewencriiaeawamauetmateirees 1.80 2.20 1.50 Castanea dentata............. 0.0.00 e eee ee 1.15 1.45 .80 Celtis occidentalis.................002.005- 1.25 1.70 1.05 Fagus americana.................0.-0e eee 1.20 1.70 75 Annieotta LD li eerste: were cesarean ait ee Ret ka Satettarrinee ao 1.35 1.70 -90 PERO PISCE ote ites alevcd a Glaraluhon ules coat ad nenisbotieud Bae 1.45 2.00 1.15 JUNG Nigra: sscenerseenasaiasavercapexans 1.10 1.65 .65 Liquidambar styraciflua.................... 1.60 2.00 1.25 -Liriodendron tulipifera..................05- 1.90 2.50 1.40 Magnolia acuminata. 1icu......... frer)...| 1.75 | 2.30 | 1.00 Nyssa sylvatica. 0.0... ee ne 1.70 2.35 1.05 Platanus occidentalis....................00. 1.90 2.30 1.30 Populus deltoides...............0.0.0000005 1.40 2.20 50 ~ .“ — grandidentata...........60e.e eee 1.00 1.35 65 os heterophylla........... 0. cece eee 1.35 1.80 1.00 . tHICHOCALPA 0... cee ee eae eee 1.15 1.90 .50 Quercus albaiscsenies cesiny eo seewgiaaeracesten 1.25 1.50 1.00 soe COCCIED eriises avasiienct 5 AsaGuaen fc mciutnen oma 1.50 2.10 1.00 re MIchaUxs..“ vexnss seaweed wend ses 1.55 1.80 1.10 46° «pati Dor ehg.ccids saree cvoinecives tan vee neadios Soiree ae 1.20 1.45 -70 GE MPRUTATD as coed cela t eee e/a 1.40 1.80 .85 e Galix migtays <7 dcwcentouateud ables mardtares amnts 85 .95 45 Tilia americana............ 00 eee 1.15 1.45 .85 Ulmus americana..............- iy hashes ery 1.50 1.90 1.15 References DeBary, A.: Comparative Anatomy, pp. 481-483. So.tEREDER, H.: Anatomy of the Dicotyledons, Vol. II, pp. 1141-1148. Grecory, E. L.: Pores of the Libriform Tissue, Bull Torrey Bot. Club, Vol. XIII, 1886, pp. 197-204; 233-244. Anonymous: Length of Wood Fibers in Broadleaf Woods, Sc. American Sup., Sept. 30, 1911, p. 211. Santo, Cart: Bot. Zeitung, Vol. XXI, No. 13, 1863, pp. 89-111. ECONOMIC WOODS OF THE UNITED STATES 21 WOOD PARENCHYMA Parenchyma occurs in the secondary xylem of all woody plants, and, with few exceptions, is disposed in two systems: (1) the vertical, composed of more or less scattered rows of cells forming the wood parenchyma; and (2) the horizontal, made up of plates of cells extending radially and at right angles to the axis— the medullary rays or pith rays. Its chief function is the distribu- tion and storage of elaborated food materials. Typical wood-parenchyma fibres (Fig. 2, F; Plate IV, Figs. 5, 6) of Dicotyledons resemble septate wood fibres, but have (1) thinner walls, (2) invariably simple, rounded pits instead of oblique, slit-like simple or bordered pits, and (3) cross walls equal in thickness to the lateral walls. The individual cells of a wood- parenchyma fibre are mostly short and prismatic, pitted with simple pits and (with the exception of the terminal ones, which are pointed) with transverse or oblique end walls. Between wood fibres and wood-parenchyma fibres are intermediate forms without septa—substitute fibres or intermediate wood fibres. Where wood parenchyma borders on large vessels it is usually much flattened as a result of the pressure of the expanding vessel segments. In such locations also are sometimes special forms termed conjugate cells because of flatly tubular processes extending from one to another slightly distant, thus uniting them (Fig. 2, H). There are special forms of wood parenchyma in which the individual cells are divided by cross walls into small chambers of approximately even size which contain solitary crystals, usually of calcium oxalate (Fig. 2, G; Plate IV, Fig. 6). Such crystals are only slightly soluble even in the strongest acids, and are very plainly visible under high magnification in both cross and longi- tudinal sections. Crystals occur in all species of Quercus, though they are commonly more abundant in the live oaks than in decid- uous species. In Juglans (Plate IV, Fig. 6), Hicoria (Plate IV, Fig. 3), and Diospyros, crystals are often quite conspicuous. Calcium-oxalate ‘crystals are also common in ray-parenchyma cells. The distribution and arrangement of wood-parenchyma fibres in different species are subject to considerable variation. As seen on cross sections of woody Dicotyledons the fibres may be (a) scattered irregularly throughout the growth ring (Plate V, Figs. 3, 5), (0) arranged in tangential lines or bands (Frontispiece, 22 ECONOMIC WOODS OF THE UNITED STATES Plate IV, Figs. 1, 2), (c) terminal, 7.e., comprising the outer limit of the growth ring (Plate III, Fig. 6; Plate V, Fig. 2; Plate VI, Fig. 2), (d) surrounding pores (Plate III, Figs. 3, 5), (e) ar- ranged in radial rows. These features are quite important in classifying woods. For example, in Fraxinus americana the pores in the late wood are usually joined tangentially by narrow bands of wood parenchyma, while in F. nigra (Plate V, Fig. 2) the pores are rarely so united. In Hicoria (Plate IV, Fig. 1) wood paren- chyma is in numerous, fine, concentric lines as distinct as the rays, while in Diospyros (Plate IV, Fig. 2) the lines are finer than the rays and very indistinct. In Tilia wood parenchyma is in tangential lines, but is not so disposed in Liriodendron, Magnolia, and isculus. In Liriodendron (Plate VI, Fig. 2) and Magnolia the outer limit of the growth ring consists of 24 rows of tan- gentially flattened wood-parenchyma fibres with very thick, copi- ously pitted radial walls. Wood parenchyma is present in the wood of all Gymnosperms except the Tazacew. The cells are invariably associated with resin formation and are usually referred to as resin cells or epithelial cells, according as they are more or less scattered or surrounding resin ducts. Resin cells are usually cylindrical or prismatic, thin-walled, with transverse terminations more or less strongly marked with simple pits. The pits in the side walls are often few and invariably simple. Resin cells can usually be distinguished on cross sections under the microscope by their thin walls, simple pits, or better by the deep color of their contents. If the section passes near enough to an end wall the simple pits therein give the appearance of a sieve plate (Fig. 10). While in most cases resin cells are invisible without the microscope, and often not readily found with it, yet in Juniperus, Taxodium, and Sequoia they are usually conspicuous, not infrequently giving rise in the first two species to wavy tangential lines in the growth ring, visible to the unaided eye. The distribution of the resin cells is variable. In some cases (e.g., Thuya) they are scattering; in others (e.g., Taxodium [Plate II, Fig. 1], Juniperus [Plate II, Figs. 3, 4], ibocedruys) y,yare disposed in well-defined zones concentric i ithe ei crow ring, being most abundant as a rule in the transition zone between early and late wood. In still other cases (e.g., T’suga) there is often a tendency of some of the resin cells to aggregation, and in ECONOMIC WOODS OF THE UNITED STATES 23 some cases the formation of imperfect resin ducts or resin cysts (Fig. 10). (See Resin Ducts.) In Pinus (Fig. 8) wood parenchyma is found only in association with resin ducts, isolated resin cells being absent; while in Larix and Pseudotsuga resin cells are occasionally found on the extreme outer face of the late wood. In Abies Yésin cells are remote and inconspicuous; in Thuya plicata they are present, though often zonate in widely separated growth rings, thus often apparently absent. In Sequoia (particularly S. sempervirens) the resin cells are partially filled with dark resin masses which appear on longi- tudinal surface as fine dotted lines, or under lens as rows of black or amber beads. References DsBary, A.: Comparative Anatomy, pp. 485-486.’ Pren#attow, D. P.: North American Gymnosperms, pp. 109-122. Boutaesr, G. 8.: Wood, pp. 28-29. Sanio, Cari: Bot. Zeitung, Vol. XXI, No. 12, pp. 93-98. Kwy, L.: Ueber Krystallbildung beim Kalkoxolat, Berichte der deutschen Bot. Gesellschaft, Vol. V, 1887, pp. 387-395. ; Gg + RAYS Medullary or pith rays, for brevity termed simply rays, appear on the cross section of a stem as radial lines crossing the growth rings at right angles and extending into the bark (Fig. 1). A few of them originate at the pith and are commonly known as primary rays. Successively, as the stem increases in size, addi- tional or secondary rays arise between those already formed. A ray may arise in the cambium layer at any point, and once formed its growth is continuous.* Under the microscope the line formed by the ray becomes a radial series of mostly elongated cells usually with transverse end walls (Plates II-IV). Viewed radially a ray appears as a muriform structure composed of from one to many tiers of brick- shaped cells (Plate IV, Figs. 5, 6): In tangential section the ends of the rays are visible, showing to advantage their height, shape, * When on cross or radial sections a ray appears to be discontinuous, it is probable that it has merely been missed by the plane of section. This empha- sizes the importance of making cross sections exactly at right angles to the axis of growth, and radial sections as nearly as possible parallel with the rays. 24 ECONOMIC WOODS OF THE UNITED STATES width, and distribution, and also the outline in cross section of the component cells (Plate III, Fig. 1; Plate IV, Figs, 3,4; Plate VI, Figs. 3, 4, 6). Ray cells are usually elongated in the radial direction. This is normally the case in Gymnosperms and usually so in the woody Dicotyledons. Not infrequently in the latter, however, part or all of the cells are upright, ¢.e., with their greatest diameter vertical, or are square. The marginal cells are sometimes upright and the interior cells radially elongated or procumbent (Fig.3). The upright cells are often very irregular, especially the outermost marginal rows; sometimes they are nearly square; again they are in pali- sade arrangement. When these upright or square cells are in Fic. 3.—Radial sections of heterogeneous rays. Tlex decidua... . WATER CONTENT OF WOOD Water occurs in living sapwood in three states, viz., (1) in the protoplasmic contents of the cells, (2) in the cell walls, and (3) as free water wholly or partially filling the lumina of cells, fibres, and vessels that have lost their contents. normally exists only in condition (2). In heartwood water In the fresh sapwood of Pinus strobus, which may be taken as fairly typical, water com- prises about half of the total weight and is distributed approx- ECONOMIC WOODS OF THE UNITED STATES 53 imately as follows: in contents of living cells, 5 per cent; satu- rating cell walls, 35 per cent; free water, 60 per cent. In a living tree the wood nearest the bark contains the most water. If no heartwood is present the decrease toward the pith is gradual; otherwise the change is quite abrupt at the sapwood limit. In Pinus palustris, for example, the weight of the fresh wood within an inch of the bark may be 50 per cent of water; that between one and two inches, only 35 per cent; that of the heartwood, only 20 per cent. The water content of any par- ticular section of a tree depends upon the amount of sapwood, and is therefore greater for the upper than for the lower portions of the stem; greater for limbs than bole; greatest of all in the roots. The water content of wood can readily be determined in the following manner: saw off a thin section of wood; weigh careful- ly on a delicate balance; dry in an oven at a temperature of 100° C. until a constant weight is obtained; reweigh. The difference between the fresh weight and the dry weight is the amount of moisture contained. Computed on a basis of the fresh weight, fresh weight — dry weight 100. fresh weight Thus if the weight of the original block of wood was twice the final weight, there was as much water as wood; in other words, one-half, or 50 per cent, of the original weight was water. The figures in the preceding paragraph are on this basis. Computed on a basis of dry weight, Per cent of moisture = inept Weight dry weight x 100. dry weight In the problem cited above the loss of moisture was 100 per cent of the dry weight. This method furnishes a constant basis for comparison, while the other varies with every change in moisture degree. Subsequent references to the per cent of moisture will refer to computation on the basis of dry weight. It is impossible to remove absolutely all the water from wood without destroying the wood. Wood is considered thoroughly dried when it ceases to lose weight in a constant temperature of 100° C., though it still retains 2 to 3 per cent of moisture, and if exposed to higher temperature will continue to give up water. Seasoning, which is essentially drying, adds appreciably to the strength, and, in slightly less proportion, to the stiffness of Per cent of moisture = 54 ECONOMIC WOODS OF THE UNITED STATES wood. A piece of green spruce timber, for example, may become four times stronger when thoroughly dried.* This is an extreme case, however, and does not apply to large timbers where check- ing, which always occurs to some extent, may counterbalance partially or even entirely the gain in strength due to drying. In small forms of hardwood material, as implement and carriage stock, and in coniferous timber in some forms, as cross- arms for telegraph poles, thorough and uniform reduction of the moisture content produces a large increase in strength. In fact a comparatively weak wood may, when perfectly dry, be much stronger than a strong wood in a green condition. Consequently tests to determine the mechanical properties of wood must, to “be comparable, take into consideration the moisture content of the specimens. By means of a great many tests the relation of the moisture degree to the mechanical properties can be approx- imated and coefficients or correction factors determined by which the strength value at any given water content can be reduced to a standard (usually 12 per cent) or other desired moisture degree. Loss of water from cell lumina alone does not affect the mechan- ical properties of wood. It is only when the cell walls begin to give up their water that increase in strength, stiffness, hardness, and resilience occur. Conversely, the absorption of water weakens wood only to the point where the cell walls become completely saturated. This critical point has been termed by Tiemann (loc. cit.) the fibre-saturation point. It varies with different treat- ments of the wood and under different conditions. The water content at this point is greater in wood previously dried and especially in wood which has been subjected to high temperature than it is in green wood. The amount of moisture at the fibre- saturation point in green wood of various species has been found by Tiemann (loc. cit.) to be between 20 and 30 (average about 27) per cent. The water content of wood materially affects durability. Since decay is produced by fungi, and to a less extent by bacteria, both of which require considerable water for their development, * In comparing the strength and stiffness of wood in green and dry condi- tions, the fact should be borne in mind that, owing to shrinkage, dry wood is more compact and contains a greater amount of wood substance per unit of volume than green wood. + Such tables have been prepared for several of the commercial woods of the United States. (See Bul. 70 and Cir. 108, U.S. Forest Service.) ECONOMIC WOODS OF THE UNITED STATES 55 all that is necessary to render even the most perishable wood indefinitely immune from decay is to keep it dry. Wood con- taining not more than 10 per cent of moisture will not decay. Rate of seasoning differs with the kind of wood and with its shape. A thin piece dries more rapidly than a thicker one; sapwood more rapidly than heartwood; a light, open wood more readily than one that is dense and heavy. Large beams or logs are exceedingly slow in drying, requiring from two to several years’ seasoning in the open air before reaching an air-dry condi- tion in the interior. Ties require from three months to a year to season, depending on the kind of timber and the climate. Much depends upon the method of piling, since boards in open piles often dry twice as fast as those in solid piles. As a result of numerous experiments by the U. 8. Forest Service upon large beams of Pinus palustris and P. teda, the following conclusions were reached (Bul. 70, p. 123): “(1) The drying-out process takes place almost wholly through the faces of the beam and not longitudinally, except near the ends. ““(2) The ratio of evaporation through a surface is proportional to the rate of growth or density of the wood near the surface, being most rapid in the case of sapwood. “(3) If the whole stick is made up of heartwood or the pro- portion of sapwood is uniform throughout, the longitudinal dis- tribution of moisture is very regular. If the proportion of sap- wood is not uniform, on the other hand, the portion containing the most sap is the most susceptible to moisture influences; 1.e., it will dry or will absorb moisture the most rapidly. “The average of two cross-sections of longleaf pine sticks, 12 by 12 inches and 8 by 16 inches and 16 feet long, which were air-dried for two years, showed an average moisture content in the outer portion, cut halfway from surface to centre, of 17.7 per cent, while the inner part contained 25.7 per cent. “From this it is quite evident that where timber of structural sizes is used, the strength ordinarily reckoned upon should not be greater than that of the green condition.” References Rota, F.: Timber, Bul. 10, U. 8. Div. Forestry, pp. 29-31. Tiemann, H. D.: The Effect of Moisture upon the Strength and Stiffness of Wood, Bul. 70, U. 8S. Forest Service, 1906, p. 144. 56 ECONOMIC WOODS OF THE UNITED STATES Tiemann, H. D.: The Strength of Wood as Influenced by Moisture, Cir- cular 108, U.S. Forest Service, 1907, p. 42. Jounson, J. B.: Timber Physics, Part II, Bul. 8, U. S. Div. of Forestry, 1893, pp, 22-24, SHRINKAGE, WARPING, AND CHECKING The volume of wood is maximum when the cell walls -are saturated with water. When this condition exists the presence or absence of free water in the cell cavities and the intercellular spaces does not affect the volume. When the cell walls begin to dry, they become thinner, but do not contract to an appreciable extent longitudinally. A dry wood cell is therefore of practically the same length as it was in a green or saturated condition, but is smaller in cross section, has thinner walls and a larger lumen. According to Nageli’s hypothesis, the cell wall is composed of aggregations in crystalline form of minute parts or micelle. These micelle are separated by films of water which become thinner as the wall dries and thicker as it swells. This shrinkage is roughly proportional to the thickness of the walls, and in con- sequence the denser woods or the denser portions of a wood shrink more than those less dense. Inasmuch as wood is not a homogeneous gaits but an intricate structure composed of cells exhibiting from moderate to extreme variation in shape, size, thickness of walls, and more especially in arrangement, it follows that shrinkage cannot be uniform throughout any specimen. Late wood, being denser, shrinks more than early wood. The ray cells, with their longest diameters for the most part at right angles to the direction of the other elements, oppose radial shrinkage and tend to produce longitudinal shrinkage of wood. Only in the tangential direc- tion are these otherwise opposing forces parallel. For this reason as well as the fact that the denser bands of late wood are tangentially continuous, while radially they are separated by alternate zones of less dense early wood, wood usually shrinks more than twice as much tangentially than it does radially. In all cases, however, shrinkage parallel to the vertical axis is very slight, one-tenth to one-third of one per cent, and is maximum in woods with curly or wavy grain or with large or very abundant rays. The following table gives the results of a series of shrinkage ECONOMIC WOODS OF THE UNITED STATES 57 tests made by Mr. Hugh P. Baker at the Yale Forest School. The figures given represent the average shrinkage resulting from reducing green wood to a kiln-dry condition and are com- puted on the basis of the original measurements. TABLE IV SHRINKAGE OF Woop ALONG DIFFERENT DIMENSIONS Area of SPECIES. a ee wae as Terence erase hi ia ¢ % p-dtimiperus virginiana. .... 0.32 2.7 2.5 5.6 6.9 5.9 Castanea dentata........ .25 3.0 3.2 4.9 11.2 ae uercusrubra........... 24 3.7 3.5 8.2 10.4 es Hicoria alba............ .04 7.4 7.5 9.2 19.4 | 19.8 T Juglans cinerea. 36 2.9 3.1 6.9 7.3 7.6 iriodendron tulipifera. . 15 4.3 4.8 9.3 12.6 | 13.7 ‘Nyssa sylvatica......... 10 6.1 6.2 11.5 17.1 | 18.0 Irregularities in shrinkage tend to cause- wood to become distorted or warped. In woods with straight grain and uniform texture the tendency to warp is minimum unless the distribution of the moisture content is very unequal. Thus the upper surface of a green board exposed to the hot rays of the sun will dry much more rapidly, and therefore becomes shorter than the lower side, causing the board to curl up at the ends. Woods with interlaced fibres or with cross or spiral grain (e.g., Nyssa, Liquidambar, Eucalyptus) always shrink unequally, and consequently require careful handling in drying to prevent serious deformation. Warp- ing due to unequal distribution of moisture may subsequently be overcome by thorough drying, but the deformation resulting from great irregularity of structure is usually permanent. In Fig. 15 is shown in somewhat exaggerated manner the deformation caused by the greater tangential shrinkage. The flat side of a log cut through the middle becomes convex (A). Boards cut from half of a log assume the form shown in (C), while a plank from the middle of a log becomes convex on both sides. This explains most of the difference in shrinkage of timbers and boards of different sizes, shapes, and manner of sawing (7.e., whether plain or quarter-sawed). When the strains due to unequal shrinkage can no longer 58 ECONOMIC WOODS OF THE UNITED STATES be accommodated by the plasticity of the wood substance, cracks or checks are formed. These are most common along the rays, since there the strains are greatest and most complex. However, when the strength of the rays is greater than the cohesive force of the cementing substance uniting the two layers of the primary cell wail, radial fracture passes through the median plane of the primary wall of the wood cells instead of along the ray. Variation in moisture content due to irregular drying results in checks, most of which are temporary, and as equilibrium becomes again established gradually close and become imper- ceptible. The more rapidly wood is dried, the greater is the tendency to check, for even if evaporation could be controlled so as to proceed uniformly throughout the specimen, the cells would not be given sufficient time to adjust themselves to the 5 ee = PNT \\ Eel NE A Fie. 15. Fig. 15.—Effects of shrinkage. A, plank cut from middle of log (boxed heart), showing double-convex surfaces and large season check through upper half. B, log cut in half, showing the flat [surface becoming convex and the appear- ance of three large season checks. C, half of a log cut into boards showing warping. changed conditions. The presence of checks in wood, no matter how imperceptible, always impairs the strength of the material. If the outer portion of a piece of wood, especially hard wood, dries much more rapidly than the inner, a hard shell is formed on the outside, while the interior retains most of its original moisture. This condition is known as case-hardening. This dry shell resists the transpiration of the moisture from the interior and retards drying, besides increasing the strains on the fibres. When the interior finally dries, the internal strains frequently become so great that large checks open up, producing a honeycombed condition. Checks which result from greater shrinkage along the tangent than along the radius are permanent and increase in size as drying progresses (Figs. 1; 15 B). They cause serious difficulty in season- ing large timbers and especially material in the round, such as ECONOMIC WOODS OF THE UNITED STATES 59 logs, poles, and posts. If seasoned too rapidly hardwood timbers may split entirely open so as completely to destroy their value. In handling such material it is a common practice to forestall such checking by driving in S-shaped metal wedges across the incipient cracks. Such damage can also be reduced by more careful piling and handling of the material. References Rots, F.: Timber, Bul. 10, U. 8. Div. Forestry, pp. 32-37. Bouuaer, G. 8.: Wood, pp. 80-88. Von Scurenck, H.: Seasoning of Timber, Bul. 41, U.S. Bu. of Forestry, 1903, p. 48. Tiemann, H. D.: Effect of Moisture on the Strength and Stiffness of Wood, Bul. 70, U. 8S. Forest Service, pp. 76-79; 116-118; 123. Baxer, Hucu P.: A Study in the Shrinkage of Wood (unpublished thesis, Yale Forest School, 1904). Carrens, C.: Zur Kenntniss der innern Structur der vegetabilischen Zell- membranen, Jahrb. fiir wissensch. Botanik, Vol. XXIII, 1892, pp. 567-636. N&ceui, K.: Ueber den innern Bau der Vegetabilischen Zellenmembranen, Sitzb. d. Akad. Wiss., Miinchen, 1864, Pt. 1, 282-326; Pt. 2, 114-170. HYGROSCOPICITY Wood substance has the property of absorbing moisture from the atmosphere. When artificially dried wood is exposed to the open air it will increase in weight, due to the addition of hygro- scopic water. Although the amount of water thus attracted is always greater than in the surrounding air, it does not remain constant, but varies with the humidity, and is equal to 8 to 16 (average 12) per cent of the dry weight of the wood. These variations are accompanied by proportionate changes in volume, that is, the wood alternately shrinks and swells, or “works.” Hygroscopicity can be reduced, but not entirely eliminated, by subjecting wood to boiling, stedming, prolonged soaking, or exposure to high temperature. This property of wood is a serious hindrance to its use in certain positions where exact fitting is permanently desired. Drawers and doors “stick” in damp weather, and become loose in dry weather, or when artificially heated and dried for con- 60 ECONOMIC WOODS OF THE UNITED STATES. siderable time. Furniture, wainscoting, interior finish, and cabinet work may be badly damaged by prolonged drying, which opens up joints, loosens tenons, and causes veneers to separate from their backing. This property may be largely overcome by soaking wood in oil or coating the surface with paint, oil, or varnish, which excludes most of the air and moisture and keeps the con- dition of the wood uniform. Light, porous woods “work’’ less than dense woods. On account of their greater porosity and light- ness, slowly grown ring-porous woods (Fig. 13) shrink and swell less than specimens of the same species more rapidly grown (Fig. 14). The presence of natural oils, gums, and pigments such as are commonly found in the heartwood of many species usually reduces the hygroscopicity of woods. References Rots, F.: Timber, Bul. 10, U. 8. Div. For., pp. 30-31. Exner, W. F.: Lorey’s Handbuch der Forstwissenschaft, Vol. II, 1903, pp. 128-129. Gayer, K.: Schlich’s Manual of Forestry, Vol. V (1908), pp. 66-75. PENETRABILITY In all green wood the cells are separated from each other by a thin membrane, the primary cell wall. The only important exceptions are the vessels between whose segments there is free communication vertically. Vessels, however, like other cells, are separated from each other and from other elements by the primary wall. This wall ordinarily persists intact unless ruptured by parenchymatous outgrowths—tyloses. It is permeable by water and certain dilute solutions which filter through slowly, but is impervious to oils and resins. Gases can enter into living cells only by going into solution, and in that condition diosmosing through the cell wall. These facts have an important bearing on the process of impregnating wocd with preservatives to prevent decay. It is not difficult to force gases or fluids through open vessels of green wood, but it is impossible to do so if they are plugged with tyloses. For example, it is very easy to blow through the vessels of green wood of most red or black oaks, even in pieces of considerable length. In green wood of the white oaks, on the other hand, ECONOMIC WOODS OF THE UNITED STATES 61 it is impossible to force any air through the vessels, even for short lengtns and with very high pressure, since in this case they are blocked with tyloses. Even in the red or black oaks, however, air cannot be forced through the other elements of green wood. When wood becomes dry its penetrability by both gases and liquids is increased to a remarkable extent. The same specimen of white oak which, while green, effectually withstood an air pressure of 150 pounds per square inch will, when dry, allow the passage of air, not only through the vessels, but also the other elements, under a pressure of 5 pounds per square inch or less. Similar effects are produced by drying any wood beyond its fibre- saturation point. This fact emphasizes the great importance of seasoning wood before attempting to impregnate it with pre- servatives. According to Tiemann (loc. cié.), the explanation of this is that the drying of the cell walls causes minute checks or slits to occur in the primary walls. The dryer the wood becomes the larger the slits and the more permeable the wood. These slits do not entirely close when the wood is resoaked, so that wood once dried cannot be restored to its original condition. Steaming is said to produce similar results, though the slits apparently are not as wide as when wood is air-dried. It is prob- able, however, that the maximum amount of slitting would result from thoroughly drying wood that had been previously steamed. Boiling green wood in oil results in more or less seasoning of the outer portions, thus allowing some penetration by the oil. Dry woods, however, differ greatly in penetrability. Light, porous woods as a rule are much easier to impregnate than dense, compact ones. Heartwood of any species offers more resistance than the sapwood, due probably to the presence in the walls of gums, resins, and other infiltrations. Tyloses, which always reduce penetrability, are mostly absent from the outer portion of sapwood even when very abundant in the heartwood of the same tree. In the wood of Gymnosperms it appears that the wood- parenchyma cells are more penetrable than the tracheids. Open resin ducts permit the entrance of fluids into the body of the wood, behaving in a manner similar to the vessels of Dicotyledons. The whole question of the penetrability of wood is extremely important in view of the increasing interest in timber preserva- tion, and comparatively little is definitely known regarding it. Experiments by the United States Forest Service are now in 62 ECONOMIC WOODS OF THE UNITED STATES progress which should add materially to the present knowledge of the subject. Reference Tiemann, Harry D.: The Physical Structure of Wood in Relation to Its Penetrability by Preservative Fluids, Bul. 120, Am. Ry. Eng. and Maintenance of Way Ass’n, Jan. 1910. CONDUCTIVITY Dry wood is a very poor conductor of heat, as is well illus- trated in its use for matches and as handles for utensils and tools subjected to various temperatures. Increase in density or in moisture content increases the conductivity of wood. Woods are most conductive in direction parallel to the grain and least so in radial direction, the ratio in some instances being as high as 2 to 1. The difference between radial and tangential direc- tions in this regard is slight, and is probably due to the fact that in a tangential direction the bands of the denser and therefore more conductive late wood are continuous, while radially they are interrupted by alternate bands of the less dense early wood. Wood in a dry condition is a non-conductor of electricity. Increase of water content reduces its value as an insulator. Light, porous woods are more resistant to the passage of electric currents than are dense woods; highly resinous woods, more than woods without resin, since resin and oil are poor conductors of electricity. Wood is a good conductor of sound, particularly in a longi- tudinal direction. The denser, the more uniform, and the dryer the wood the greater is its ability to transmit sound. Unsound- ness and decay materially reduce this property. References GayYER, Karu: Schlich’s Manual of Forestry, Vol. V, 1908, pp. 78-79. Exner, W. F.: Lorey’s Handbuch der Forstwissenschaft, Vol. II, p. 117. Matuey, ALPHONSE: Traité d’Exploitation Commerciale des Bois, Vol. I, Paris, 1906, pp. 63-65. NorpiincER, H.: Die Technischen Eigenschaften der Holzer, pp. 56-114. RESONANCE “Tf a log or scantling is struck with the ax or hammer, a sound is emitted which varies in pitch and character with the ECONOMIC WOODS OF THE UNITED STATES 63 shape and size of the stick, and also with the kind and condition of wood. Not only can sound be produced by a direct blow, but a thin board may be set vibrating and be made to give a tone by merely producing a suitable tone in its vicinity. The vibra- tions of the air, caused by the motion of the strings of the piano, communicate themselves to the board, which vibrates in the same intervals as the string and reénforces the note. The note which a given piece of wood may emit varies in pitch directly with the elasticity, and indirectly with the weight, of the wood. The ability of a properly shaped sounding-board to respond freely to all the notes within the range of an instrument, as well as to reflect the character of the notes thus emitted (i.e., whether melodious or not), depends, first on the structure of the wood, and next on the uniformity of the same throughout the board. In the manufacture of musical instruments all wood containing defects, knots, cross grain, resinous tracts, alternations of wide and narrow rings, and all wood in which summer and spring wood are strongly contrasted in structure and variable in their proportions are rejected, and only radial sections (quarter-sawed, or split) of wood of uniform structure and growth are used. “The irregularity in structure, due to the presence of relatively large pores and pith rays, excludes almost all our broad-leaved woods from such use, while the number of eligible woods among conifers is limited by the necessity of combining sufficient strength with uniformity in structure, absence of too pronounced bands of summer wood, and relative freedom from resin. “Spruce is the favored resonance wood; it is used for sounding- boards both in pianos and violins, while for the resistant back and sides of the latter, the highly elastic hard maple is used. Preferably resonance wood is not bent to assume the final form; the belly of a violin is shaped from a thicker piece, so that every fiber is in the original in as nearly an unstrained condition as possi- ble, and therefore free to vibrate. All wood for musical instruments is, of course, well seasoned, the final drying in kiln or warm room being preceded by careful seasoning at ordinary temperatures often for as many as seven years or more. The improvement of violins, not by age, but by long usage, is probably due, not only to the adjustment of the numerous component parts to each other, but also to a change in the wood itself; years of vibrating enabling any given part to vibrate much more readily.” * *Roth, F., Timber, Bul. 10, U. S. Div. For., pp. 24-25. 64 ECONOMIC WOODS OF THE UNITED STATES COLOR When wood is first formed it is almost, if not entirely, color- less, as may be observed in the outermost growth rings in any species. After a year or two it usually becomes yellowish, and still later when changed into heartwood a decided deepening of color results. Exceptions to this rule are rather numerous, for example, Picea, Tsuga, Abies, Salix, Alnus, Betula, Ilex, and 4ésculus exhibit little or no contrast in color between heartwood and sapwood. In all species the sapwood has a very limited range of color and shade, but the heartwood exhibits great varia- tion, from the chalky white of Ilex opaca to the ebony black of old Diospyros virginiana, with practically all intermediate colors, shades, and tints. In many woods the demarcation in color between heartwood and sapwood is very sharp and distinct, while in others the transition is gradual. In some instances (e.g., Sequoia, Ilex, Catalpa, Cladrastis lutea) the color is uniform, while in others (e.g., Liriodendron, Liquidambar, Swietenia) it is variable not only in different specimens, but in different portions of the same piece. The golden yellow of Toxylon shows narrow streaks of red; Liquidambar shows black streaks that usually give the finished lumber a handsome watered effect; Liriodendron varies from deep iridescent blue to yellowish brown; Robinia varies from light straw-colored to deep golden yellow like Toxylon; Taxodium is sometimes nearly black, often yellowish, reddish, brown, or mottled. The deep-colored wood of Juniperus fre- quently exhibits streaks of white sapwood, the intermingling resulting from the fluted periphery of the stem. It is generally true that depth of color of woods is a criterion of durability. Thus the dark heartwood of Juniperus, Sequoia, Prosopis, Toxylon, Robinia, and Morus is very resistant to decay, while that of Salix, Populus, Tilia, Aisculus, Acer, Fraxinus, and Nyssa is perishable. The deeper color of the heartwood is due to the infiltration or deposition in the cell walls and lumina of gums, resins, pigments, tannin, and other substances. To these is ascribed the greater durability of wood, since sapwood is invariably not durable under exposure. In some instances, how- ever (e.g., Chamecyparis, Taxodium, Catalpa, Sassafras), the infiltrated substances tend to prevent decay without greatly deepening the color of the heartwood. ECONOMIC WOODS OF THE UNITED STATES 65 Color adds greatly to the value of wood for interior finish, cabinet work, marquetry, and parquetry. It is a very common practice to stain wood artificially. Light-colored and therefore less valuable wood of mahogany, such as commonly grows in the United States and Mexico, is often darkened; Ilex opaca is readily stained black to resemble ebony; Betula lenta, when properly stained, is a good imitation of mahogany; in fact, by the applica- tion of stains and finishes the variations in color and shade that can be produced in woods is practically unlimited. It is also possible by the introduction of certain chemicals to color the sapwood of a living tree. For some uses of wood lack of color is prized. This is especially true of pulpwood, since coloring matter, if present, must be bleached out. Color is also undesirable in certain grades of flooring. In handles and spokes dark color is considered a defect, since it indicates heartwood, which is usually (but erroneously) thought to be weaker than the colorless sapwood. All woods darken upon exposure to the atmosphere, probably due to the oxidation of the coloring matters. The rich golden yellow of Toxylon and Morus becomes a dark or russet brown; the sapwood of Alnus oregona turns reddish brown; Pinus monti- cola and P. strobus often become vinous red, especially near the end of an exposed piece of wood. On this account the natural color of a wood can only be seen on fresh-cut sections. Prolonged immersion in water causes wood to darken—some turning gray, others almost black. Some woods (e.g., Cladrastis lutea, Prosopis, Sequoia, Juglans) impart color to water in which they are soaked. The color of many others can be removed by treatment with NaOH or other chemicals, but it is often necessary to reduce the wood to pulp before it can be bleached. Many tropical woods (e.g., Clorophora tinctoria, Hematoxylon campechianum, Cesalpina, Pterocarpus) contain coloring principles of value in the arts for dyeing, though they have been largely superseded by aniline dyes. Of indigenous woods, Toxylon pomiferum and several species of Xanthorylum are sometimes employed for this purpose, usually as adulterants of old fustic (Clorophora). Color is often of great assistance for diagnostic purposes, though the range of variation and difficulty of description must always be taken into consideration. Unless otherwise stated, the colors mentioned in the key refer always to the fresh cross section 5 66 ECONOMIC WOODS OF THE UNITED STATES of a piece of dry wood. The character of the demarcation in color between heartwood and sapwood, whetherjsharp or gradual, is often an important feature, though usually not exhibited on very small specimens. The character and amount of coloring matter ex- tracted by treatment with NaOH is sometimes made use of in identification. Abnormal discoloration of wood usually denotes disease. The black check in Tsuga heterophylla is the result of insect attacks. The reddish-brown streaks so common in Hicoria are mostly the result of injury by birds. The bluing of the sapwood of many soft woods is due to the attacks of fungi. Many fungi can be determined specifically by the characteristic color they impart to wood. References Rotu, F.: Timber, Bul. 10, U. 8. Div. For., p. 24. Gayer, K.: Schlich’s Manual of Forestry, Vol. V (1908), pp. 43-46. Hawnavsex, T. F.: The Microscopy of Technical Products. Me tt, C. D.: Fustic Wood, Cir. 184, U. 8. Forest Service. Exner, W. F.: Lorey’s Handbuch der Forstwissenschaft, Vol. II, pp. 105-111. Norpuincer, H.: Die Technischen Eigenschaften der Hélzer, pp. 46-51. GLOSS OR LUSTRE Gloss or lustre of wood refers to the manner in which light is reflected by the wood elements. The fibres of the bast are more lustrous than the wood fibres. The fibre of flax is highly lustrous, while that of cotton is dull. Similar variation occurs in the elements of different woods. For example, the woods of Fagara, Rhus, and Toxylon are highly lustrous; those of Acer, Betula, and Robinia less so; while those of Juglans nigra, Sequoia, Fagus, and Platanus are dull. The wood of Picea possesses a pearly lustre; that of Guatacum and Tazodium is rather greasy or waxy. In some cases the lustre varies in different parts of the wood or on different planes. The late wood of Juniperus virginiana exhibits a frosted lustre on tangential surface. The rays on quarter-sawed wood of several species, particularly the oaks, are so lustrous in contrast to the other elements as to give rise to the term “silver grain,’ while the rays themselves are called “mirrors.” Woods with high natural lustre are usually capable of taking a high polish. Lustre is a sign of soundness ECONOMIC WOODS OF THE UNITED STATES 67 in wood, for incipient decay causes wood to become dull and “dead.’’ Sound wood in thin sections is translucent and exhibits double refraction. The presence of rosin in wood increases its translucency. é References Gayer, K.: Schlich’s Manual of Forestry, Vol. V (1908), pp. 47, 79. Exner, W. F.: Lorey’s Handbuch der Forstwissenschaft, pp. 111-112. No6rpuincer, H.: Die Technischen Eigenschaften der Hélzer, pp. 46-51. SCENT OR ODOR Every wood when fresh possesses in some degree a characteristic scent, though in a great many cases it is so weak or fleeting that it escapes notice. Odor depends upon chemical compounds (e.g., ethereal oils and tannin) which form no part of the wood itself. Ordinarily it is more pronounced in heartwood than in sapwood. It is also greater in wood in a green condition than when seasoned, more evident on moist surfaces than on dry. Upon prolonged exposure to air, or when submerged in water, wood gradually loses its scent. In some cases the loss is complete throughout; in others only the outer portions are affected. Woods deriving their odors from the presence of ethereal oils, as is the case in many cedars, apparently may be kept indefinitely and still emit their characteristic odors when a fresh surface is exposed. Upon exposure to the air for a short time some green woods (e.g., Quercus) acquire a disagreeable, soured odor, probably due to the decomposition of certain organic compounds. Woods in process of decay emit various odors, sometimes very disagreeable (e.g., Populus), sometimes not unpleasant (e.g., Quercus), but always different from the natural scent characteristic of the sound wood. The fumes of burning wood are occasionally characteristic. Resinous woods, as Pinus, give off an odor of tar. The woods of Juniperus virginiana and Chamecyparis lawsoniana burn with a pungent, spicy scent, giving the latter a special value for match- sticks. The woods of Cercidium and Parkinsonia give off very penetrating, disagreeable fumes when burned, reducing materially their desirability for fuel. The scent of certain woods renders them commercially valuable. Cigars are believed to be considerably improved by being kept in 68 ECONOMIC WOODS OF THE UNITED STATES cedar boxes. The scent of cedar (Juniperus virginiana, Chame- cyparis lawsoniana, and C. nootkatensis) is apparently disagreeable to moths and other insects, making the wood desirable for cabinets, wardrobes, chests, and drawers where furs and woolen clothes — are kept. Cedar shavings are also employed for the same purpose. Loss of scent from the exposed surface of the wood soon seriously impairs the efficiency of the wood for this purpose. For some purposes, especially as receptacles for wines, liquors, drinking- water, and oils, meats, fish, butter, and other foodstuffs, highly- scented wood is undesirable since it is apt to taint the contents. While scent is often a very valuable aid to the identification of wood, its utility is lessened by the difficulty and often impos- sibility of describing an odor so that one unfamiliar with it would be able to recognize it. Such descriptions are necessarily limited to comparisons with well-known scents which are usually inade- quate. The scent of the wood of Pinus is resinous or like tur- pentine; that of Juniperus and Chamecyparis thyoides aromatic, like cedar oil; that of Chamecyparis nootkatensis, C. lawsoniana, and Libocedrus decurrens spicy-resinous; that of dark-colored, waxy specimens of Taxodium, like rancid butter; that of Catalpa some- what like kerosene; that of Viburnum lentago and V. prunifolium very disagreeable and pungent. The following genera and species usually can be recognized by their odor alone: Juniperus, Chamecyparis thyoides, C. lawson- tana, Libocedrus, Thuya, Tsuga canadensis, Sassafras, Viburnum, and Catalpa. With a keen sense of smell others may be recog- nized; for example, Pinus, Tarodium, Quercus, Castanea, Ulmus, and Betula. Prominent among exotic species characterized by pronounced scents are the camphor trees (Cinnamomum camphora, Dryobalanus camphora, Camphora glanduliferum), Indian sandal- wood (Santalum album), and violet-wood (Acacia homophylla). References Gayer, K.: Schlich’s Manual of Forestry, Vol. V (1908), pp. 47-48. Roru, F.: Timber, Bul. 10, U. 8. Div. For., p. 24. Krats, Paut: Gewerbliche Materialkunde, Vol. I, Die Hélzer, p. 652. Exner, W. F.: Lorey’s Handbuch der Forstwissenschaft, Vol. II, pp. 116-117. Norpuincer, H.: Die Technischen Eigenschaften der Holzer, pp. 51-53. ECONOMIC WOODS OF THE UNITED STATES 69 TASTE Wood substance itself, being insoluble in water or weak alkaline solutions, is necessarily tasteless. The characteristic taste of certain woods is due then to soluble substances deposited in the cell lumina or infiltrated into the cell walls. In any wood the most pronounced flavor is obtained from the sapwood; it is also more pronounced in green material than in dry. This is probably due to the fact that the substances giving wood its flavor were in solution or soluble form in the living sapwood. When submerged in water they may be leached out, and when exposed to air, oxidized. Taste is occasionally helpful in identifying woods, though, like odor, it cannot be described with accuracy. The wood of Libocedrus decurrens has a very spicy flavor; that of Pinus palus- tris terebinthic; that of Chamecyparis lawsoniana spicy-resinous; that of Sassafras rather spicy. The wood of Castanea has no special flavor, but on account of the tannin in it, has an astringent effect on the mouth. al LIST OF GENERAL CLASSIFICATIONS OF WOODS Bouteer, G. 8.: Wood (2d edition, London, 1908), pp. 41-54. Branpis, D.: Forest Flora of North-West and Central India, Preface, p. xxx. See also Gamble’s Manual of Indian Timbers, Introduction, p. xviii. DeBary, A.: Comparative Anatomy of the Vegetative Organs of the Phanerogams and Ferns (English edition, Oxford, 1884), pp. 495-496. (Classification condensed from Sanio.) Foxwortuy, Frep W.: Key to Philippine Commercial Woods, The Philippine Journal of Science, C. Botany, Vol. II, No. 5, Oct. 1907, pp. 364-369. HanavseEk, T. F.: The Microscopy of Technical Products (English edition, New York, 1907), pp. 211-248. Hartic, R.: Die Unterscheidungsmarkmale der wichtigeren in Deutschland wachsenden H6lzer, Munich, 1883. See Gamble’s Manual of Indian Timbers, Intr., p. xvii. Hartic, Tu.: Anatomie und Physiologie der Holzpflanzen (Ber- lin, 1878), pp. 177-179. 70 ECONOMIC WOODS OF THE UNITED STATES Kienttz, M.: Schliissel zum Bestimmen der wichtigsten in Deutschland wachsenden Holzer, Munich, 1879. Krais, Paut: Gewerbliche Materialkunde, Vol. I, Die Hélzer (Stuttgart, 1910), pp. 657-731. Maruizv, M.: Flore Forestiére (4th edition). For translation of classification, see Gamble’s Manual of Indian Timbers, Intr., p. xvii. : Table pour Determiner les Coupes Transversales des Bois Indigénes les plus Utiles 4 l’Aide de la loupe ou de la Simple Vue. See Beauverie’s Le Bois (Paris, 1905), Vol. I, p. 64. Mutter, N. J. C.: Atlas der Holzstructur (Miinden, 1888), pp. 54-55; 90-91. Prenuattow, D. P.: North American Gymnosperms (Boston, 1907), Part IT. Rotu, Fitrsert: Timber, Bul. 10, U. 8. Div. of Forestry, Wash- ington, D. C., 1895. See also Johnson’s Materials of Construction (New York, 1902), Chap. XIII. SANIO, Cart: Vergleichende Untersuchungen iiber des Holz- k6rpers, Bot. Zeit., Vol. X XI, No. 51, 1863, pp. 401-408. Scuacut, H.: Der Baum (Berlin, 1853), pp. 377-396. SHROEDER, J.: Schliissel zur Bestimmung des Coniferen-Holzes nach den histologischen Merkmalen. See Tursky’s Tabellen zur Bestimmung des Holzes und der Zweige in blattlosem Zustande der wichtigsten Baum- und Straucharten, Nach- richten der Petrowski’schen Agricultur- und Forstakademie Moskau, Jahrgang VII, 1883, No. 1, pp. 35-74. Strzevecki, H.: Kluez do rozpoznawania drewna wazniejszych drzew i drzew6w le$nych i ogrodowych (Key for determining the wood of the most important trees and shrubs), Kosmos, Organ d. poln. Naturforscher-Ver. Copernicus, Vols. VII- VIII, 1881, pp. 385-387. Warp, Marsuauu: Timber and Some of its Diseases (London, 1889), pp. 54-59. See also Gamble’s Manual of Indian Timbers (London, 1902), Intr., p. xviii. Wiesner, Jutius: Die Rohstoffe des Pflanzen Reiches, Vol. II (Leipzig, 1903), pp. 145-146. ECONOMIC WOODS OF THE UNITED STATES 71 PUBLICATIONS DEALING WITH THE CHARACTER- ISTICS OF WOODS ABROMEIT, JOHANNES: Ueber die Anatomie des Eichenholzes. Berlin, G. Bernstein, 1884. AHERN, GEORGE P.: The Uses of Philippine Woods, Bul. 11, Philippine Bu. Forestry, Manila, P. I. 1911. Bautrour, Epwarp: The Timber Trees and Fancy Woods, as also the Forests of India, and Eastern and Southern Asia (8d ed.). Madras, Higgenbotham & Co., 1870. Bastin, Epson S., anp TrimBie, Henry: A Contribution to the Knowledge of the North American Conifere. Reprint, American Journal of Pharmacy, Vols. LX VIII-LXIX, 1896-7. BaTerRDEN, J. R.: Timber. New York, D. van Nostrand & Co., 1908. Beavuverig, J.: Le Bois. Vol. I-II. Paris, Gauthier-Villars, 1905. —: Le Bois Industriels. Paris, O. Doin et fils, 1910. Boutesr, G. 8.: Wood: a Manual of the Natural Histories and Industrial Applications of the Timbers of Commerce (2d ed.). London, Edward Arnold, 1908. Branpis, Str Drerricu: Indian Trees. London, A. Constable & Co., 1906. Brirron, N. L.: North American Trees. New York, Henry Holt & Co., 1906. Bruanp, M., er au: Notices sur le Débit et les Emplois du Chataignier, des Erables, du Fréne, des Ormes, de L’Aune, du Bouleau, du Saule, du Tilleul, du Tremble, du Charme, de L’Aliser, du Cerisier-Merisier, du Cornouiller, du Coudrier, du Micocoulier, du Poirer, du Pommier, du Robinier, du Sorbier- Cormier. Paris, Imprimerie Nationale, 1878. Burcerstein, A.: Anatomische Untersuchungen samoanische Hélzer, K. Rechinger, Botanische und Zoologische Ergebnisse einer wissenschaftlichen Forschungsreise nach den Samoainseln, dem Neuguinea-Archipel und den Salomoninseln. IV. Teil, Denkschriften d. Mathemat. naturwissensch. Klasse kais. Ak. Wiss. LX XXIV, Wien, 1908. CHARPENTIER, PauL: Timber: a Comprehensive Study of Wood in All its Aspects (trans. from the French by Joseph Kennell). London, Scott, Greenwood & Co., 1902. 72 ECONOMIC WOODS OF THE UNITED STATES CroizeTTe-Desnoyers, M.: Notice sur le Debit et les Emplois des Principales Espéces de Pins. Paris, Imprimerie Nationale, 1878. Dupont, A. E., anp La Grys, B. pre: Les Bois: Indigénes et Ktrangers. Paris, J. Rothschild, 1875. Ene er, A.: Einige Nutzhélzer Kameruns, I, Olacexe, Notizblatt d. kénigl. bot. Garten und Museums zu Dohlem (Berlin), Appendix XXI, No. 1, Jan. 20, 1909. Exner, Wiuuram F.: Die Technischen Eigenschaften der Hélzer (Chap. VI of Lorey’s Handbuch der Forstwissenschaft, Vol. II. Tiibingen, H. Laupp, 1903). Foxwortny, Frep W.: Philippine Woods, Phil. Journal of Sci., C. Botany, Vol. II, No. 5, Manila, P. I., October, 1907. GamBteE, J. 8.: Manual of Indian Timbers (rev. ed.). London, S. Low, Marston & Co., 1902. GayER, Karu: Forest Utilization (Vol. V of Schlich’s Manual of ' Forestry; trans. from the German by W. R. Fisher; 2d ed.). London, Bradbury, Agnew & Co., 1908. Hatt, Witiiam L., anp Maxwetu, Hu.: Uses of Commercial Woods of the United States: I. Cedars, Cypresses, and Sequoias; Bul.95; II. Pines, Bul. 99. U. 8. Forest Service, Washington, D. C., 1911. Harms, H.: EHinige Nutzhdlzer Kameruns: II, Leguminosa, Notizblatt d. konigl. bot. Garten u. Museums zu Dohlem bei Steglitz (Berlin). Appendix XXI, No. 2, July 15, 1911. Hartic, Ropert: Timbers and How to Know Them; translated from the 3d German edition by Dr. William Somerville. Edin- burgh, D. Douglas, 1890. Hartic, THEopor: Anatomie und Physiologie der Holzpflanzen. Berlin, Julius Springer, 1878. Hay, R. D.: The Principal Timbers of New South Wales and Their Uses. Sydney, 1906. HEssELBARTH, Gutpo: Beitriége zur Vergleichenden Anatomie des Holzes. Leipzig, Druck der Rossberg’schen Buchdruckerei, 1879. Hovuau, Franxurn B.: The Elements of Forestry. Cincinnati, The Robert Clarke Co., 1898. Hovuau, Romeyn B.: American Woods (Sections and Text). Vols. I-XII. Lowville, N. Y., the author, 1893-1911. ECONOMIC WOODS OF THE UNITED STATES 73 Hovuacu, Romeyn B.: Handbook of the Trees of the Northern States and Canada East of the Rocky Mountains. Lowville, N. Y., the author, 1907. Husert, E.: Le Bois et le Liége, Paris, J. B. Bailliére & Sons, 1902. Jaccarp, P.: Etude Anatomique de Bois comprimés, 48 pp., illus., plates. Zurich, Switzerland, F. Lohbauer, 1910. Janssonius, H. H.: Mikrographie des Holzes der auf Java vor- kommenden Baumarten, Pub. Departments fiir Landwirtschaft in'Buitenzorg. Leiden, E. J. Brill, Part I, 1906; Part II, 1908; Part ITI, 1911. Jepson, Wiis L.: The Silva of California (Vol. II, Memoirs of the University of California). Berkeley, University Press, 1910. Korrmeiger, H., anp Unutmann, F.: Das Holz. Leipzig, Quelle & Meyer, 1910. Krais, Pauu: Gewerbliche Materialkunde: Die Holzer. Stutt- gart, Felix Krais, 1910. Laris, E.: Rohholzgewinnung und Gewerbseigenschaften des Holzes. Vienna and Leipsic, 1909, pp. 184. LASLETT, Tuomas: Timber and Timber Trees, Native and Foreign (2d ed.; revised and enlarged by H. Marshall Ward). London and New York, Macmillan & Co., 1894. MacKenzin, D. F.: The Identification of Timber: with a Uniform Series of Photo-micrographs. Trans. Highland and Agr. Soc. of Scotland, Ser. 5, Vol. XII, 1900, pp. 183-224. McTourx, Micnar.: Wood of British Guiana. Georgetown, Gov- ernment report, 1902. . Mann, James: Australian Timber: its Strength, Durability, and Identification. Melbourne, Walker, May & Co., 1900. Marrtin-LavieNe, E.: Recherches sur les Bois de la Guyane. Leur identification 4 l’aide des caractéres extérieurs et micro- scopiques. Trav. Lab. Mat. med. Ec. sup. Pharm., Paris, VI, 1910, pp. 1-181. Maruey, ALPHONSE: Traité d’Exploitation Commerciale des Bois. Vols. I-II. Paris, Lucien Laveur, 1908. MeEti, Ciayton D., anp Brusu, W. D.: Quebracho and Its Substitutes. Cir. 202, U. 8. Forest Service, Washington, D. C., 1912. 74 ECONOMIC WOODS OF THE UNITED STATES Mor izr, Josepy: Beitraége zur vergleichenden Anatomie des Holzes. Wien, 1876. ————: Anatomie der Baumrinden. Vergleichende Studien. Berlin, Julius Springer, 1882. : Die Rohstoffe des Tischler- und Drechslergewerbes. Theil I: Das Holz. Cassel, Theodor Fischer, 1883. Mone, CHARLES, AND Rotu, Finipert: The Timber Pines of the Southern United States, together with a Discussion of the Struc- ture of their Wood. Bul. 13 (rev. ed.), U. S. Div. Forestry, Washington, D. C., 1897. Miutier, N.J.C.: Atlas der Holzstructur. Halle A.S8., Wilhelm Knapp, 1888. Norpiincer, H.: Die Technischen Eigenschaften des Holzer fiir Forst und Baubeamte. Technologen und Gewerbtreibende. Stuttgart, J. G. Cotta, 1860. Prenuatitow, Davin P.: A Manual of the North American Gymno- sperms, exclusive of the Cycadales, but together with Certain Exotic Species. Boston, Ginn & Co., 1907. Pincuot, GIFFORD, AND ASHE, W. W.: Timber Trees and Forests of North Carolina. Bul. 6, N. C. Geol. Survey, Chapel Hill, N. C., 1897. Rattinesr, K. K.: Die Nutzhélzer der Vereinigten Staaten, I, Die Nadelhélzer, Wiesbaden, Verlag Forstbiro, 1910. Rizzi, P.: Technologia forestale ed Utilizzazione dei Boschi. Milan, F. Vallardi, Vol. I, 1897; Vol. II, 1898. Rots, Fiursert: Timber: an Elementary Discussion of the Char- acteristics and Properties of Woods. Bul. No. 10, U.S. Div. of Forestry, Washington, D. C., 1895. Sarcent, Cuas. 8.: Report on the Forests of North America (exclusive of Mexico). Vol. IX, Tenth Census, Washington, D.C., 1884. : The Woods of the United States, with an Account of the Structure, Qualities and Uses (Jesup Collection). New York, D. Appleton & Co., 1885. : The Silva of North America: a Description of the Trees which Grow Naturally in North America, exclusive of Mexico. Vols. I-XIV. Boston and New York, Houghton Mifflin Co., 1891-1902. ECONOMIC WOODS OF THE UNITED STATES 75 SarcenT, Cuas. S.: Manual of the Trees of North America (exclusive of Mexico). Boston and New York, Houghton Mifflin Co., 1905. Scuacut, Hermann: Der Baum. Studien tiber Bau und Leben der Hoheren Gewachse. Berlin, G. M. F. Miiller, 1853. ScHROEDER, Jutius: Das Holz der Coniferen. Dresden, 1872. SKINNER, W.: Description, etc., of Indian and Burmese Timbers. 1862. Snow, C. H.: The Principal Species of Wood (2d ed.). New York, John Wiley & Sons, 1908. SoLEREDER, Hans: Systematic Anatomy of the Dicotyledons. Vols. I-II (Eng. trans.). Oxford, Clarendon Press, 1908. STEPHENSON, WitLiIaM: The Trees of Commerce (rev. ed.). London, W. Ryder & Son, 1908. Stone, Hersert: The Timbers of Commerce and Their Iden- tification. London, W. Ryder & Son, 1904. Supwortu, Grorce B.: Forest Trees of the Pacific Slope. U.S. Forest Service, Washington, D. C., 1908. AND Meti, Cuayton D.: The Identification of Im- portant North American Oak Woods, based on a Study of the Secondary Wood. Bul. 102, U. 8. Forest Service, Wash- ington, D. C., 1911. —_—___—-: “Colombian Mahogany,” Its Characteris- tics and Its Use as a Substitute for True Mahogany. Cir. 185, U. 8. Forest Service, Washington, D. C., 1911. ——_______—— : Circassian Walnut and Its Substitutes. Cir. 210, U. 8. Forest Service, Washington, D. C., 1912. —_—_—_——_—: Identification of North American Walnut Woods. Bul. 120, U. S. Forest Service, Washington, D. C., 1912. —: Distinguishing Characteristics of North American Gumwoods, based on the anatomy of the secondary wood. Bul. 103, U.S. Forest Service, Washington, D. C., 1911. Troup, R. 8.: Indian Woods and Their Uses, Indian Forest Memoirs, Vol. I, No. 1. Imperial Forest Research Institute of India, 1909. Warren, W. H.: The Strength, Elasticity, and Other Properties of New South Wales Hardwood Timbers. N. 8. W. Dept. of Forestry, Sydney, 1911. 76 ECONOMIC WOODS OF THE UNITED STATES Wuitrorp, H. N.: The Forests of the Philippines. Part I, Forest Types and Products. Part II, The Principal Forest Trees. Bul. 10, Philippine Bu. of Forestry, Manila, P. I., 1911. WIEsNER, JuLIus: Die Rohstoffe des Pflanzen Reiches. Vol. II. Leipzig, Wilhelm Engelmann, 1903. Witpa, Hermann: Das Holz: Aufbau, Eigenschaften und Ver- wendung, Leipzig, G. J. Géschen, 1910. PUBLICATIONS DEALING WITH THE USES OF AMERICAN WOODS Betts, H. 8.: Properties and Uses of the Southern Pines. Cir. 164, U. S. Forest Service, Washington, D. C., 1909, pp. 30. Cuing, McGarvey, anp Knapp, J. B.: Properties and Uses of Douglas Fir. Bul. 38, U.S. Forest Service, Washington, D. C., 19t1, pp. 75. Dope, Cuartes Ricuarps: A Descriptive Catalogue of Manu- factures from Native Woods, as shown in the Exhibit of the U.S. Department of Agriculture at the World’s Industrial and Cotton Exposition at New Orleans, La. Special Report No. 10, U. 8. Dept. Agr., Washington, D. C., 1886, pp. 84. GouLp, C. W., anp Maxwetu, Hu.: The Wood-using Industries of Mississippi. Lumber Trade Journal, March 15, 1912, pp. 19-29. Hawi, Wiuuiam L., anp MaxweE i, Hvu.: Uses of Commercial Woods of the United States: I. Cedars, Cypresses, and Sequoias. Bul. 95, U. 8. Forest Service, Washington, D. C., 1911, pp. 62. ——__—_—_—————: Uses of Commercial Woods of the United States: II. Pines. Bul. 99, U. 8. Forest Service, Washington, D. C., 1911, pp. 96. Hatcu, Cuarues F.: Manufacture and Utilization of Hickory, 1911. Cir. 187, U.S. Forest Service, Washington, D. C., 1911, pp. 16. AND Maxwewti, Hu.: The Wood-using Industries of Missouri. Reprint, St. Louis Lumberman, March 15, 1912, pp. 68-82. Lazensy, Wituiam R.: The Economic Uses of Wood. Pub. Ohio State Univ., Columbus, O., 1904, pp. 14. ECONOMIC WOODS OF THE UNITED STATES 77 MacMituian, H. R.: Wood-using Industries [of Canada], 1910. Bul. No. 24, Forestry Branch, Dept. Int., Ottawa, 1912, pp. 42. Maxwe .u, Hv.: The Wood-using Industries of Louisiana. The Lumber Trade Journal, New Orleans, La., Jan. 1, 1912, pp. 19-33. ———: The Wood-using Industries of Maryland. Bul. Maryland State Board of Forestry, Baltimore, Md., 1910, pp. 58. ————-: A Study of the Massachusetts Wood-using Industries. Pub. by State of Mass., Boston, 1910, pp. 38. Utilization of Osage Orange. Pub. by Farm Wagon Dept., Nat’l Implement and Vehicle Ass’n., U. 8. A., 1911, pp. 14. OakLEAF, Howarp B.: Wood-using Industries of Oregon, with Special Reference to the Properties and Uses of Oregon Woods. Pub. -by Oreg. Conservation Ass’n, Portland, Ore., 1911, pp. 46. —— —: Washington’s Secondary Wood-using Industries. Pacific Lumber Trade Journal, Seattle, 1911, pp. 8. Stmmons, Rocrer E.: The Wood-using Industries of Illinois. University of Illinois, Urbana, IIl., 1911, pp. 164. : A Study of the Wood-using Industries of Kentucky. Pub. by Dept. Agr., Labor and Statistics, Frankfort, Ky., 1910, pp. 74. ———-: Wood-using Industries of North Carolina. Econ. Paper No. XX, N. C. Econ. and Geol. Survey, Raleigh, 1910, pp. 74. SmitH, Franxuin H.: A Study of the Wisconsin Wood-using Industries. Pub. by Forestry Dept., Madison, Wis., 1910, pp. 68. ‘i i Surrace, G. T.: The Commercial Woods of the United States and Their Uses. Reprint, Bul. Geog. Soc. of Phila., Vol. VIII, No. 3, July, 1910, pp. 20-34. PART II KEY TO THE ECONOMIC WOODS OF THE UNITED STATES I. Homogenrous or Non-porous Woops: GYMNOSPERMS; ConrFrers; “Sorr Woops” Vessels absent; wood composed mostly of tracheids uniform in structure and arranged in definite radial rows. Growth rings defined by the greater density of the late wood. Resin cells and resin ducts present or absent. Rays very fine, numerous, incon- spicuous. A Resin ducts, both vertical and horizontal, present. Rays with ‘ tracheids. 1 With clear demarcation _in_« color between heartwood and sapwood. a Resin ducts plainly visible to the unaided eye, numerous often well distributed; tyloses present; epithelium thin- walled.. Resin cells absent. Wood with characteristic but not always pronounced resinous odor. Pine.’ a! Little contrast between early and late wood. Wood soft to medium; only moderately resinous; texture uniform; color light or reddish, variable. Upper and lower walls of the few and small ray tracheids smooth (Figs. 4-5). Pits present on the tangential walls of the tracheids of the late wood. Soft Pine Group. Notre.—tThe letters in parentheses following the specific names refer to the map (Plate I, Natural Forest Regions of the United States), and in- dicate in a general way the distribution of the species. (P), Pacific Coast Forest; (R), Rocky Mountain Forest; (N), Northern Forest, general; (L), Lake States Forest; (A), Appalachian Forest; (C), Central Hardwood Forest; (8), Southern Forest; (T), Tropical or Sub- tropical Forest; (n), north; +(s), south. Where more than one region is indicated, the more important is placed first. 78 ECONOMIC WOODS OF THE UNITED STATES 79 a? Radial walls of each ray-parenchyma cell with 1-2 large simple pits communicating with each adjacent wood tracheid (Fig. 4). Wood straight-grained; rate of growth widely variable. White Pine Group.’ Pinus strobus L. (N); monticola Dougl. (P); lam- bertiana Dougl. (P); flexilis James (P); albicaulis Eng. (R, P); strobiformis Eng. (R). a® Color cream white. to reddish brown. Texture fine. Resin ducts fairly conspicuous, appearing on longi- tudinal surface as straw-colored or light-brown lines. Without sugary exudations. Pits on lateral walls of ray-parenchyma cells large, 1-2 (mostly 1) per tracheid. White Pine. P. strobus L. (N),; monticola Dougl. (P). Flay where — (footer b? Color yellowish white to very light brown. Tex- ture comparatively coarse. Resin ducts conspic- uous, appearing on longitudinal surface as dark lines. Sugary exudations and sugar pockets common. Pits on lateral walls of ray-parenchyma cells comparatively small, 1-2 (mostly 2) per tracheid. Sugar Pine. P. lambertiana Dougl.(P).* b? The radial walls of each parenchyma cell with 3-6 small semi-bordered pits communicating with each adjacent wood tracheid (Fig. 5). Texture very fine. ood cross-grained and of very slow growth. Fox- tail and Nut Pine Group. P. quadrifolia Parl. (P); cembroides Zuec. (R); edulis Eng. (R)*; monophylla T. & F. (R); balfouriana Murr. (P); aristata Eng.(P). b* Decided contrast between early and late wood. Wood very hard to rather soft; resinous; texture uneven; color variable, but_mostly darker than in soft_pines. Upper and lower walls of the small and numerous ray tracheids dentate or reticulate (Figs. 6, 7). Pits rarely present on tangential walls of the tracheids of the late wood. Pitch Pine Group. a? The radial walls of each ray-parenchyma cell with 1-2 large simple pits communicating with each adjacent wood tracheid (Fig. 6). Wood light, rather soft, fairly strong, medium-textured, not highly resinous. RTD 80 ECONOMIC WOODS OF THE UNITED STATES Growth rings rather wide and uniform. Color light red. Sapwood thin. — Norway or Red Pine. Pinus resinosa Ait. (L). b? The radial walls of each ray-parenchyma cell with 3-6 rather small simple pits communicating with each adjacent wood, tracheid (Fig. 7). Hard Pine Group. a* Wood mostly heavy, hard, strong, rather tough; unevenly textured. Sapwood variable. Southern Pines.* ° a* Wood usually extremely heavy and hard; very resinous. a> Growth rings mostly narrow, uniform in width and outline. Color uniform, dark ‘reddish yellow to reddish brown. Sapwood thin. Parts of wood often becoming ‘‘fatty’” with resin. ‘Longleaf Pine. P. palustris Mill. (8). b® Growth rings mostly wide, variable. Dark straw-color with tinge of flesh-color. Sap- wood thick. Cuban Pine. P. heterophylla (Ell.) Sudw. (S). b* Wood of medium weight and hardness. Less resinous than in preceding. a> Growth rings mostly of medium width, but variable; often irregular in width and out- line. Wood rather variable; fairly hard and strong. Color whitish to reddish brown. Late wood dense. Sapwood widely vari- able; usually rather thick. Shortleaf Pine. P. echinata Mill. (S). b> Growth rings widely variable, often _ex- tremely broad, irregular, somewhat double. Wood variable from somewhat hard, com- pact, and strong, to light, coarse, and brashy; late wood often not dense. *It is difficult and very often impossible to make specific distinctions in this group by macroscopic inspection, and the microscopic features so far recognized are of little assistance. ECONOMIC WOODS OF THE UNITED STATES 81 Color yellowish to reddish or orange brown. Sapwood very thick. Loblolly Pine. P. taeda L. (S).° b? Wood comparatively light, soft, not strong, brittle. Texture usually coarse, occasionally medium to fine. Sapwood usually thick; rarely thin. P. murrayana “O. C.” (R, P); ponderosa Laws. (R, P); radiata Don. (P)°; attenuata Lem. (P); sabi- niana Dougl. (P)"; coultert Lamb. (P); torreyana Parry (P); chihuahuana Eng. (R);_ arizonica Eng. (R); rigida Mill. (N); divaricata Ait. (N); pungens Michx. f. (N); clausa Sarg. (S); glabra Walt. (8); virginiana Mill. (C, 8). a* Tangential surface: showing conspicuous ‘‘peb- bly” or “‘bird’s-eye” grain. Resin ducts very small, scattering. Texture fine. Color light, yellow or nearly white. Sapwood thin. Prop- erties of wood fairly uniform. Lodgepole Pine. P. murrayana “O. C.” (R, P). b‘ Tangential surface usually normal. Resin ducts comparatively large and numerous. Tex- ture medium to coarse. Color widely variable from pale lemon to orange brown. Sapwood thick. Wood variable from heavy, hard, and coarse to light, soft, fine, and non-resinous like white pine. Western Yellow Pine. P. ponderosa Laws. (R, P).” b Resin ducts mostly inconspicuous, not numerous, irregularly distributed or grouped; chiefly without tyloses; epithelium thick-walled. Resin cells inconspicuous, near the outer limit of the late wood. a a! Resin ducts very small, mostly invisible to unaided eye; round in cross section. Marked contrast in color be- tween _heartwood_and sapwood. Sapwood thin. Tra- cheids without spirals.* a’ Color yellowish brown. Texture medium. * Tamarack. Larix americana Michx. (N). * The occasional occurrence of spirals in the tracheids of the late wood of Larix has been noted by Bailey, Bot. Gaz., Vol. XLVIII, pp. 47-55. 6 82 ECONOMIC WOODS OF THE UNITED STATES b? Color red to reddish brown. Texture coarse and harsh. Western Larch. L. occidentalis Nutt. (R). b' Resin ducts somewhat larger, usually visible t j eye; oval in cross section. Sapwood rather thick. Spiral markings on the tracheids, at least in early wood; marginal ray tracheids with spirals. a? Grain usually straight; sometimes wavy. Wood of two kinds: (1) growth rings narrow, wood reddish yellow in color and of fairly uniform texture; rather light and soft, easy to work. PetGoah ane: wide, wood dark ‘red i _in color and of uneven texture; early wood 0 open » and. “weak, late wood flinty; difficult to work. Douglas Fir. Pseudotsuga taxifolia Brit. (P, R).* b? Grain usually not straight; wood often cross-grained; color always red. Wood usually less dense, rays more numerous, and the pits on the ray-parenchyma cells larger than in the preceding. Red Fir. P. macrocarpa Mayr. (P). 2 Without clear demarcation in color between heartwood and sapwood. a Resin ducts mostly small, scattered; epithelium thick- walled; tyloses often present. Resin cells absent. Tra- cheids without spirals.* Wood mostly light and soft, fine and even-textured. — Spruce. a' Color white or ight; uniform throughout. Little contrast in density between early and late wood. Resin ducts scarcely visible without lens, being of same color as surrounding wood. a? Growth rings mostly_wide-t White Spruce. Picea canadensis Mill. (N). * The sporadic development of wood parenchyma on the outer surface of the late wood, and the occurrence of spiral thickenings of the tracheids in both early and late wood of Picea have been noted by Bailey, loc. cit. Tt Owing to the fact that rate of growth is largely determined by external factors, any attempt to classify woods on a basis of width of ring is at best unsatisfactory and is resorted to here only because constant features of dis- tinction are apparently wanting. ECONOMIC WOODS OF THE UNITED STATES 83 b? Growth rings of medium. width, though often very narrow near centre of tree. Red Spruce. P. rubens Sarg. (N). ce? Growth rings mostly very narrow throughout. - Black Spruce. P. mariana Mill. (N). b'_Color distinctly reddish, fading gradually outward. Moderate contrast in density between early and late wood; transition gradual. Resin ducts plainly visible to unaided eye, appearing on cross section as white dots against colored background. Sitka Spruce. P. sitchensis T. & M. (P). B Resin ducts normally absent; sometimes present as a result of injury, the vertical ducts arranged tangentially in a compact row (Fig. 10). Ray tracheids present or absent. 1 With clear demarcation in color between heartwood and sap- wood. a Resin cells numerous, often conspicuous to unaided eye. Tracheids without spirals. Wood light and soft to moder- ately so; lustre dull. a! Odorless and tasteless. Texture coarse and harsh. Sapwood thin, straw-colored to nearly white, often streaked with fine purplish lines of resin cells. Resin masses in resin cells appear (under lens) on longitudinal surface as rows of black or amber beads. Sequoia.” a’ Wood deeply colored, purplish, Growth rings mostly very narrow. Texture fairly coarse. Big Tree. Sequoia washingtoniana Sudw. (P).*° b? Wood less deeply colored; light cherry. Growth rings variable from wide to narrow. Texture very coarse. Resin masses more prominent than in preceding. Redwood. S. sempervirens Engl. (P)."" b! Odor aromatic, pungent. Texture fine to very fine. Sapwood white or nearly so; not-streaked. Resin cells small, without bead-like appearance. a? Growth rings uniform, usually rather wide; late wood rather thin, but very conspicuous; rarely doubled. Resin cells fairly numerous, zonate, mostly in late 84 ECONOMIC WOODS OF THE UNITED STATES wood; usually not visible under lens. Rays. 1-8, mostly 3-5, cells high. Texture fine. Color pale. reddish brown or roseate. Odor and taste spicy- resinous; characteristic. ee ees /4/- YF Incense Cedar. Libocedrus decurrens Torr. (P)." b? Growth rings usually very irregular in width and out- line; often eccentric; late wood usually extremely thin, inconspicuous; very commonly doubled or trebled (Plate II, Fig. 4). Resin cells very numerous, deeply colored, visible under lens; mostly zonate (Plate II, Fig. 3), often giving rise to 1-3 tangential lines visible to unaided eye. Rays 1-20 cells high, very irregular. Texture very fine. Odor aromatic, characteristic. Taste not pronounced. Juniper; Cedar.” a’ Color deep reddish brown or purple, becoming dull 7 brown upon exposure. Red Cedar. Juniperus £5- L . virginiana L. (N, C)”; Southern Red Cedar. barbadensis L. (S); scopulorum Sarg. (R). b? Color pale to medium dark brown, usually tinged with red. J. occidentalis Hook. (R); utahensis Lem. (R) adpacnY phica Torr. (Rs); monosperma Sarg. (Rs); californica Carr. (P)- 747-0 b Resin cells absent. Tracheids with spirals. Woods with _high lustre. Odorless and tasteless, Texture fine. a! Color reddish brown to rose red. Wood heavy, hard, strong, and elastic. Growth rings variable; mostly eccentric; often sinuous. Yew. a? Tracheids very small, thick-walled. Color bright orange or rose red; thin sapwood pale yellow. Tazus brevifolia Nutt. (P). b? Tracheids larger, rather thin-walled. Color brown- ish red; thin sapwood nearly white. T. floridana Nutt. (S). b! Color clear bright yellow. Growth rings uniform. a? Wood light, soft, not strong. California Nutmeg. Tumion californicum Greene (W). b? Wood heavy, hard, strong. JRO- FF Stinking Cedar. T. taxifoliwm Greene (S). ECONOMIC WOODS OF THE UNITED STATES 85 2 Without clear demarcation in color between heartwood-and sapwood. a Heartwood little if any darker than the sapwood. a' Ray tracheids present. Hemlock. a’ Wood harsh and splintery; often knotty and cup shaken; rather cross-grained and not easy to work. Contrast between early and late wood very decided (Plate II, Fig. 2); transition abrupt. Odor rancid. Color light brown with slight reddish hue. Resin cysts normally absent. Eastern Hemlock. Tsuga canadensis Carr. (N). . b? Wood rather soft, not _splintery; usually clear, free ‘from. shake; straight-grained; easy to work. Con- trast between early and late wood less decided, and transition more gradual than in preceding. .Odorless or somewhat sour. Color very pale brown with pinkish hue to late wood. Resin cysts often present. Western Hemlock. T. heterophylla Sarg. (P).?* b! Ray tracheids absent.* Fir.” a? Wood light, soft, weak; growth rings often very wide. Color white or straw, occasionally pale brown. in old trees. White and Balsam Fir Group. Abies frasert Lindl. (S, A); Balsam Fir. balsamea Mill. (N)+~ Alpine Fir. lasiocarpa Nutt. (R); Lowland Fir. grandis — Lindl. (P); White Fir. concolor Parry (P); amabilis_ Forb. (P). Le b’ Wood moderately to very heavy, hard, and strong. Color brownish red in general appearance; early wood straw-colored; Iate wood and rays with reddish tinge. Red Fir Group. Noble Fir. A. nobilis Lindl. . (P); Red Fir. . magnifica Murr. (P). 7 3 hx yar" b Heartwood more despiy colored than the sapwood, fading gradually outward. a! Odorless or~slightly rancid; tasteless. Color widely variable; yellowish, reddish, brown, variegated or * The occasional occurrence of ray tracheids in Abies balsamea has been noted by Penhallow, North American Gymnosperms, p. 253. 86 ECONOMIC WOODS OF THE UNITED STATES almost black. Wood variable from light and soft to moderately heavy and hard; often “ pecky,” i.e., riddled with fungus galleries. Smooth surface of sound wood looks and feels greasy or waxy. Rays numerous, rather prominent; WROTE without tracheids. Resin cells numerous and prominent; commonly zonate (Plate II, Fig. 1). Pits on wood tracheids very small, often irregularly disposed; mostly in two rows. //Q-% Bald Cypress. Tazxodium distichum Rich. (8).” b! Odor resinous or aromatic; agreeable. Tasteless, or with marked resinous flavor. Wood very light and soft. j a? Great variation in depth of color between sapwood and heartwood, that of the latter varying from dark purplish brown to dark brown tinged with red; dark wood often streaked with lighter shades. Sapwood usually dingy white with light shades of brown inter- mingled. Lustre dull. Odor like oil of cedar; very mild. Tasteless or nearly so. Resin cells present, though often zonate in widely separated growth rings, thus often apparently absent. Rays rather narrow, somewhat prominent; without tracheids. <2 FR Western Red Cedar. Thuya plicata Don. (P).” b? Moderate variation in depth of color between heart- wood and sapwood. Resin cells zonate or scattering. a? Color light clear yellow, uniform. Odor aromatic, resinous. ‘T'aste spicy, very characteristic. Wood light and soft to moderately heavy and hard. a‘ Ray tracheids present in low rays. Color very light. Texture very fine. Odor moderately pronounced. Yellow Cedar. Chamecyparis 240~ K nootkatensis Spach. (P).” b‘ Ray tracheids absent. Color somewhat deeper. Texture moderately fine. Odor very pro- nounced. ZL4/ KK. .Port Orford Cedar. C.lawsoniana Parl. (P).”* b? Color pale brown or-reddish; intermingling of lighter and darker shades common (esp. in Thuya occidentalis). Odor like oil of cedar, but very mild. No pronounced taste. Wood very light and soft, ECONOMIC WOODS OF THE UNITED STATES 87 usually spongy and difficult to cut smoothly a across the grain. Rays without tracheids.* White /#iaitf~. << Cedar. C. thyoides B. 8. P. (N, 8)"; Arborvitee. Thuya occidentalis L. (N).”8 ee II. Hererocrenrous or Porous Woops: DicoTyLEDONS; BroaDLeaF Woops; Harpwoops Vessels present. Wood composed of three to six kinds of ele- ments not uniform in structure and rarely arranged in definite radial rows. Growth rings often defined by zonate arrangement of large pores in eazly wood as well as by the greater density of the late wood. Resin cells and resin ducts absent. Rays variable from very narow to very broad. A Ring-porous Woods. Pores in early wood zonate, large, and conspicuous, rarely small and inconspicuous; in late wood small or few and scattered. Rays uniseriate or widely variable. _Tex- ture medium to very coarse. 1 Pores in radial lines branching more or less toward the periphery of the growth ring; pores small to very small. Pores in early wood in one to several rows. Wood paren- chyma in fine tangential lines. a Broad rays absent; rays uniform, uniseriate, inconspicuous, 5-15 cells high. Wood rather light, moderately soft, stiff but not strong. ~ a' Pores in early wood few, small, usually round or nearly so, and rather widely separated in a single row. Wood with roseate hue. Odorless and tasteless. Western Chinquapin. Castanopsis chrysophylia deC. (P). b! Pores in early wood very numerous, usually oval or elliptical and in a wide zone. Color brown. Odor very mild. Astringent taste. Chestnut. Castanea dentata Borkh. (C, N)”®; Chinquapin Chestnut. pumila Mill. (8S). b Broad rays present; intermediate rays mostly uniseriate, invisible without lens (Plate III, Fig. 1). Wood_heavy, hard, strong. Odor characteristic. Oak.” Udor characteristl * The occasional occurrence of ray tracheids in the low rays of C. thyoides has been noted by Penhallow, North American Gymnosperms, p. 232. 88 ECONOMIC WOODS OF THE UNITED STATES a Pores in early wood_in few (1-3) rows, usually not b _ crowded; transition to smaller pores of late wood abrupt. Pores in late wood very small, with thin walls and angular outlines (Plate II, Fig. 5); numerous, crowded, not open, appearing as irregular, grayish radial bands widening outward; tyloses abundant in all pores. Large rays often very high, maximum 5 inches. ep oe Se White Oak Group. a? Radial bands of small pores comparatively broad, more or less fan-shaped, often joined tangentially. White Oak. Quercus alba L. (C, N) (Frontispiece)*'; Bur Oak. macrocarpa Michx. (C, N) (Fig. 14); Post Oak. minor Sarg. (C, A, 8); Chestnut Oak. prinus * L. (N, C)®; Overcup Oak. lyrata Walt. (C, 8); Durand Oak. breviloba Sarg. (S). b? Radial bands of small pores comparatively narrow and seldom joined tangentially. Swamp White Oak. Q. platanoides (Lam.) Sudw. (N, C); Cow Oak. michauatt Nutt. (C, 8). Pores in early wood mostly in several (3-5) rows ‘crowded; transition to smaller pores ii Tate wood gradual. Pores in late wood comparatively large, with thick walls and “circular outlines (Plate IT, Fig. 6); rather few, not crowded, open, usually visible to un- aided eye. Tyloses usually scarce or wanting, some- times abundant (esp. in Q. marilandica). Large rays comparatively low, rarely 1 inch high. Pere wer ah Pye ee Black or Red Oak Group.* a? Radial bands of small pores comparatively broad, often branched. Pin Oak. Q. palustris Muench. (C); Water Oak. nigra L. (8S, C); Shingle Oak. imbricaria Michx. (C, N); Spanish Oak. digitata Sudw. (8, C); Turkey Oak. catesbei Sudw. (8); marilandica Muench. (C, 8). b? Radial bands of small pores narrow, mostly un- branched. Red Oak. Q. rubra L. (C, N); Spotted Oak. terana Buckl. (C, 8); Black Oak. velutina Lam. * For Evergreen Oak group see ‘‘ Diffuse-porous Woods.” ECONOMIC WOODS OF THE UNITED STATES 89 (C, N); Scarlet Oak. coccinea Muench. (C, N); Willow Oak. phellos L. (8S). d_arranged tangentially in ccnspicuous festoons or concentric bands, usually continuous, wavy; the pores minute or small. Pores in early wood in single row or in zone of 2-3 (rarely more) rows. Wood parenchyma not in tangential lines. a Rays very distinct; the larger 6-8 cells wide and 30-50 —célis high, conspicuous; the smaller 1-2 cells wide and 6-10 cells high, inconspicuous; ae ceca wane gree ! “coarse. semen EOC a! Color yellow or grayish yellow. Hackberry. Celtis occidentalis L. (C, N, 8). b! Color yellowish green. Sugarberry. C. mississippiensis Bosc. (8). b Rays rather indistinct; the larger 3-5 cells wide and 15-30 cells high, appearing much smaller than the larger rays of the preceding; the smaller uniseriate and 3-5 cells high;. homogeneous. Heartwood distinct; color brown, often with reddish tinge. Texture medium to 6oa coarse. So Bim a! Pores in early wood forming a broad tangential band of 3 or more rows; pores large, numerous, conspicuous. Texture coarse. "Wood easy to split. (Inner bark thick, mucilaginous.) Slippery Elm. Ulmus pubescens Walt. (C, N, 8). b! Pores in early wood usually in a single tangential row; occasionally more in wide growth rings. a? Pores in early wood large, forming a continuous row (Plate III, Fig. 2). Texture coarse. Wood difficult to split. Rather light. White Elm. U. americana L. (C, N). b? Pores in early wood small to minute, the larger ones few and rather widely separated in a band of small pores. Texture medium. - Wood hard. a? Growth rings distinct. a‘ Bands of small pores rather few; narrower than intervening spaces. Wood very hard, com- 90 ECONOMIC WOODS OF THE UNITED STATES pact. Fairly easy to split. Rock or Hickory Elm. U. racemosa Thomas (C, N). b* Bands of small pores numerous; wider than intervening spaces. Wood moderately hard: Difficult to split. Winged Elm. U. alata Michx. (S, C). b® Growth rings indistinct. Bands of small pores broad, very wavy, and branched. Wood hard. Difficult to split. Cedar Elm. U. crassifolia Nutt. (S). 3 Pores in late wood small, distributed singly, in groups, of mostly short, broken (occasionally cantina) ore Ag Teta tines, Rays fairly uniform, fine to minute. d parenchynfa around pores or extending wing-like from pores in late wood, often uniting them into irregular tangential lines. Outer limit of growth ring consists chiefly or exclu- sively of wood parenchyma. a Pores in early wood very small, indistinct, rather widely separated in a single row. Wood very light, soft, weak, difficult to cut smoothly across the grain. Water Ash. Fraxinus caroliniana Mill. (8). b Pores in early wood large, conspicuous, usually in a rather broad zone 3-10, rarely 1-2, rows wide. a! Rays narrow (1-5 cells), inconspicuous; almost invisible on cross section to unaided eye. Color pale or dull brown to nearly white; not very deep or striking. a? Odorless and tasteless. Medium to very heavy and hard. Pores in late wood isolated, or In groups of 2-3, “or united by wood parenchyma into mostly short tangential lines, especially in outer portion of growth ring. Color brown to white, sometimes with reddish tinge to late wood. Sapwood very thick, white. Demarcation in color between heartwood and. sap- wood not clear. Rays homogeneous. Ash. a? Pores in late wood usually joined tangentially by wood parenchyma. Wood very hard and strong. a‘ Pores in early wood in rather broad zone; numerous. ECONOMIC WOODS OF THE UNITED STATES 91 a®> Lines of pores in late wood short, narrow, composed of few open pores and considerable wood parenchyma; mostly near periphery of growth ring; occasionally absent or very indistinct in narrow rings. White Ash. Fraxinus americana L. (C, N). Lines of pores in late wood long, narrow, prominent, composed of abundant wood parenchyma and inconspicuous pores; usu- ally well distributed. Blue Ash. F. quad- rangulata Michx. (C); Red Ash. pennsyl- vanica Marsh. (N). b‘ Pores in early wood in rather narrow zone; not numerous. Lines of pores in late wood quite long and conspicuous; well distributed. Green Ash. F. lanceolata Borkh. (C,N, §). b? Pores in late wood rarely joined by wood paren- chyma. Wood of medium hardness and strength. on b a’ Pores in early wood in very broad zone, com- monly one-half the width of the growth ring. Pores in late wood isolated, few, large. Color dark brown. Wood comparatively soft and weak. Ray cells small. Black Ash. F. nigra Marsh. (C, N) (Plate V, Fig. 2). b‘ Pores in early wood in zone of medium width, commonly one-third the width of the growth ring. Pores in late wood in radial groups of 2-5 and near periphery of growth ring somewhat tangentially grouped. Color light brown; sap- wood with reddish tinge. Wood harder and stronger than preceding. Ray cells large. Oregon Ash. F. oregona Nutt. (P). b?_Odor characteristic; somewhat resembling that of kerosene. Tasteless. Wood very light and soft. Pores in late wood in rather large groups and near periphery or growth ring in broad, comparatively short (sometimes continuous) tangential bands; in very wide rings pores often indistinctly grouped. Color light to medium dark brown, satiny; very 92 ECONOMIC WOODS OF THE UNITED STATES thin sapwood lighter. Demarcation in color be- tween heartwood and sapwood distinct. Rays het- erogeneous. Common Catalpa. Catalpa catalpa Karst. (C, 8); Hardy Catalpa. speciosa Ward. (C).* b! Rays narrow. (1-3 cells), very fine but fairly distinct. Color light orange brown, a? Odor aromatic or spicy, usually quite pronounced. Often with characteristic pleasant taste (most pro- nounced in inner bark). Wood light and soft. Pores in late wood in numerous small groups radially, and toward periphery of growth ring tangentially, elon- gated. Sapwood very thin, nearly white. Clear demarcation in color between heartwood and sap- wood. Occasional marginal cells very large, ovate or round; rays heterogeneous (Fig. 3, A). Sassafras. Sassafras sassafras Karst. (S, C).* c! Rays variable, but usually quite distinct, mostly 5-9 cells wide. Color of wood variab t_us striking. a? Color golden yellow te_greenish—bspemn very thin sapwood white or greenish. Wood extremely hard (like horn), very heavy and strong, Texture fine. Vessels densely plugged with-tyloses. Pores in early wood in comparatively narrow zone, irregular, inter- spersed with abundant wood parenchyma. Pores in outer portion of late wood in large groups joined tangentially by wood parenchyma. Rays _ hetero- geneous. : a’ Color always golden yellow, though darkening upon exposure; vertically streaked with narrow red stripes. Color slightly soluble in water. Lustre high. Wood tasteless. Rays fine, numer- ous, rather inconspicuous. Osage Orange. Toxy- lon pomiferum Raf. (C, 8S) (Plate ITI, Fig. 4).* b3 Color varying from golden yellow to brown, often greenish, usually uniform in single specimen; rarely striped with red. Color of golden yellow wood readily soluble in water, wet wood giving off stain when applied to white paper or cloth. ECONOMIC WOODS OF THE UNITED STATES 93 Lustre not so high as in preceding. Taste of wood “leguminous.” Rays variable from minute to medium, irregular, rather conspicuous. Black Locust. Robinia pseudacacia L. (C, A) (Plate III, Fig. 3).*° b? Color orange yellowto yellowish brown, becoming rus- ‘set brown upon exposure; thin sapwood nearly white. Wood moderately ae hard, and strong. Texture coarse. Pores in early wood often in rather wide zone. Pores in late wood minute, in groups of 3-6; not joined by wood parenchyma. Tyloses present, fairly abundant. Rays very prominent on radial section, often high; heterogeneous. Odorless and tasteless. Red Mulberry. Morus rubra L. (C, 8S) (Plate V, Fig. 1). ce? Color light cherry red to reddish brown; thin to moderately thick sapwood greenish. Wood heavy, hard, and strong. Texture very coarse. Pores in early wood in broad zone. Tyloses absent or rare. Gummy substance in vessels. Odorless and tasteless. Rays mostly homogeneous. a} Rays distinct, but not conspicuous; fairly uni- orm; ray cells very small, uniform. Pores in outer portion of late wood small to minute, usually in groups of 5-20; rarely jomed by wood paren- chyma into bands; individual pores visible under lens. Kentucky Coffee Tree. Gymnocladus dioicus Koch (C) (Plate III, Fig. 5). b? Rays conspicuous; variable; ray cells com- paratively large, variable. Pores in outer portion of late wood minute; usually in groups of 10-25; often jomed by wood parenchyma into short, wavy (sometimes continuous) tangential bands; individual pores mostly invisible under lens. Honey Locust. Gleditsia triacanthos L. (C, 8) (Plate III, Fig. 6). 4 Pores in late wood jsolated or fairly evenly distributed; not in groups or lines; comparatively large, often approaching mm size hae of early wood. Pores in early wood moderately 94 ECONOMIC WOODS OF THE UNITED STATES large, not abundant, usually in very irregular zone; in narrow growth rings rather diffuse. Rays fairly uniform,not con- spicuous, abundant. Wood parenchyma in fine tangential lines. a Wood elements in tier-like arrangement (Plate IV, Figs. 4, 5), producing on longitudinal surface fine, wavy cross- markings readily visible to unaided eye. Lines of wood parenchyma indistinct, finer than the rays (Plate IV, Fig. 2). Crystals present, rather small; mostly in long rows. Rays in stories; fairly uniform in height; 1-2 (rarely 3) seriate; cells large (Plate IV, Fig. 4). Color of wood of old trees dark brown to black; thick sapwood (making up all or nearly all of young trees) yellowish, usually streaked with black. Wood fibres thick-walled. Wood very heavy, hard, and strong. Tyloses absent. Persimmon. Diospyros virginiana L. (S, C). b Wood elements not in tier-like arrangement. Lines of wood parenchyma as distinct as the rays. Crystals large; usually solitary. Rays irregularly disposed; not uniform in height or shape;- 1-5 seriate; gells small (Plate IV, Fig. 3). Color of wood brown to reddish brown; thick sapwood white, often with dark reddish streaks. Tyloses present. Hickory.*® a! Wood very hard, heavy, tough, strong, resilient... Wood fibres very thick-walled. Shagbark. Hicoria ovata Brit. (C, N) (Plate IV, Fig. 3); Shellbark. laeiniosa Sarg. (C); Mocker Nut. alba Brit. (C, N,-8); Pignut. glabra Brit. (C, N, 8). b' Wood hard, heavy, brittle, fairly strong. Wood fibres comparatively thin-walled. a? Growth rings not clearly defined. Large pores not in well-defined zone; scattered; approaching diffuse- porous. | Water Hickory. H. aquatica Brit. (8). b? Growth rings clearly defined. Large pores in fairly well-defined zone, 1-several pores wide. Pecan. H. pecan Brit. (8S, C); Nutmeg Hickory. myristice- formis Brit. (S); Bitternut. minima Brit. (C, N, 8). B Diffuse-porous Woods. Pores numerous; usually not prom- inent on cross section; diffused throughout growth ring instead ECONOMIC WOODS OF THE UNITED STATES 95 of collected in decided ring or zone in the early wood; occa- sionally more numerous and very often somewhat larger in the early wood. Growth rings principally defined by the greater density of the late wood or by the radial flattening of the outermost rows of wood fibres; often indistinct; sometimes absent. 1 Growth rings absent or indistinct; when present not cor- responding to annual periods and not separable into early and late wood. a Broad rays present. a’ Color light to dark brown, sometimes tinged with red. Wood very heavy, hard, strong, and tough; not easy to work. Pores slightly variable in size; rather small but distinct, arranged in radial rows or groups usually con- tinuous from year to year. Large rays mostly rather low, broad; often appearing on tangential surface as aggregations of small rays interspersed with wood fibres. Evergreen Oak Group.*® _a Wood parenchyma in very distinct tangential lines. Tanbark Oak. Quercus densiflora H. & A. (P)*; hypoleuca Eng. (Rs). b? Wood parenchyma not in tangential lines or, if so, not distinct. Live Oaks. Q. virginiana Mill. (S), chrysolepis Liebm. (Ps), agrifolia Nee. (Ps). b Broad rays absent. a! Color rich reddish brown to light brown; widely vari- able. Wood variable from light and soft to very hard, heavy (sp. gr., .56-.88), and strong; brittle; often highly figured. Pores uniform in size, rather large and conspicuous, equally distributed, solitary or in radial groups of 2-3; often filled with dark-red resin. Rays fine but distinct, producing silver grain on radial surface; deeply colored; heterogeneous; often in horizontal seriation producing rather undulating cross lines on tangential surface. Wood parenchyma in rather widely separated conspicuous tangential lines, limiting growth rings. Mahogany. Swretenia mahagoni Jacq. (T).*! b' Color dark yellowish brown with decided greenish tinge, often streaked ; nearly black in old trees. Wood ex- ® 96 ECONOMIC WOODS OF THE UNITED STATES ceedingly heavy (sp. gr., 1.14), harder than horn, strong, brittle, cross-grained, very difficult to work. Pores somewhat variable in size, small and inconspic- uous, scattered, solitary; usually filled with. dark-green resin. Rays very fine, uniseriate, deeply colored, almost invisible; in perfect horizontal series, producing cross lines very distinct under lens. Wood parenchyma in numerous, fine, wavy tangential lines. Lignumvitz. Guaiacum sanctum L. (T). an c! Color light brown or straw. Wood very hard (sp. gr., .83), heavy, tough, and strong like hickory; fibres much interlaced; wood rather difficult to work. Pores variable in size, conspicuous, irregularly distributed in wavy lines or groups, open. Alternate bands of very dense and less dense wood produce zones somewhat resembling annual rings. Rays very fine, not deeply colored, almost invisible; irregularly distributed. Wood parenchyma not in tangential lines. Blue Gum. Lucalyptus globulus Lab. (Ps, T).” 2 Growth rings usually distinct, corresponding to annual periods; late wood recognized by its greater density, tan- gential flattening of the outermost rows of fibres, and some- what fewer or smaller pores. a Pores comparatively large in early wood, distinct to unaided eye, diminishing in size and number toward periphery of growth ring; often approaching ring-porous. a' Rays fine, 1 seriate, few to 30 cells high, scarcely visible to unaided eye; mostly homogeneous. Pores solitary or in radial groups of 2-5; often in diagonal rows. Vessels without spirals; tyloses present, very dark-colored. Wood parenchyma in numerous, very fine, short, tangential lines; chambered cells bearing crystals common (Plate IV, Fig. 6). a? Wood heavy and hard, moderately stiff and strong. Odor mild, but characteristic. Color rich dark or chocolate brown. Sapwood rather thin to thick. Black Walnut. Juglans nigra L. (C, A). ECONOMIC WOODS OF THE UNITED STATES 97 b? Wood light, soft, not strong. Odorless. Color light chestnut brown with dark tangential zones. Sap- wood very thin. Butternut. J. cinerea L. (C, N).* b Pores very small to minute, indistinct, usually fairly uni- form in size and distribution throughout growth ring. a! With conspicuously broad rays. a? Broad rays rather few, appearing as aggregated small rays (Plate V, Figs. 3, 4). Wood without “silver grain.” a? Broad rays grouped, confined to short radii. Inter- mediate rays abundant, very fine, indistinct, irregular. Wood parenchyma in indistinct tan- gential lines. Pores in early wood in irregular groups which appear to unaided eye as white dots; not crowded; arrangement somewhat obliquely radial; pores fewer and smaller in late wood. Vessels with spirals. Growth rings decidedly un- dulating. Color yellowish white. Wood heavy, hard, very tough, difficult to split. Blue Beech. Carpinus caroliniana Walt. (N, C).“ ct) b® Broad rays distant, fairly evenly distributed. Intermediate rays very numerous, uniseriate, in- visible to unaided eye. Wood parenchyma not in tangential lines. Pores more numerous in early wood, showing slightly radial arrangement; some- what crowded. Vessels without spirals. Growth rings not undulating or only slightly so; not very clearly defined. Color light brown tinged with red; exposed surface of lighter colored sapwood soon stained reddish brown upon exposure. Wood light, soft, moderately strong, brittle. Red Alder. Alnus oregona Nutt. (P) (Plate V, Figs. 3, 4).* b? Broad rays numerous, non-aggregated. Wood with conspicuous “silver grain” on radial surface. a® Rays practically all broad, mostly 10-15 cells; abundant; fairly regularly disposed; of deeper color, than surrounding tissue, producing very con- spicuous “‘silver grain”; homogeneous. Wood 98 ECONOMIC WOODS OF THE UNITED STATES b* parenchyma in indistinct tangential lines. Pores crowded. Color light brown, often with dark stripes or “feather grain.’””’ Wood medium to heavy, moderately hard, usually cross-grained, difficult to split. Sycamore or Buttonball. Pla- tanus occidentalis L. (C, N, 8), racemosa Nutt. (Ps), wrightit Wats. (Rs). With only part of the rays broad; variable; irregularly distributed; intermediate rays visible, mostly uniseriate; heterogeneous. ‘Silver grain” less conspicuous than in preceding. Wood paren- chyma in indistinct tangential lines. Pores crowded. Color pale reddish brown to white with reddish tinge; uniform. Wood heavy, hard, strong, usually fairly straight-grained. Beech. Fagus americana Sw. (C, N, 8). b! Without conspicuously broad rays. a? Rays very distinct; variable, 1—7 cells wide. ae b? Wood fibres with spirals. a' Color chalky white. Pores irregularly distrib- uted in long radial lines. Vessels with spirals; perforations scalariform. Rays colorless; hete- rogeneous. Wood parenchyma not in distinct lines. Wood of medium weight, hard and tough. Holly. Ilex opaca Ait. (S, C). Wood fibres without spirals. a‘ Wood parenchyma not in tangential lines. Vessels with spirals; perforations simple. a® Color rich reddish brown or vinous. Pores numerous, solitary, or in groups, often radial, of 2-6; usually more abundant in early wood, producing a light-colored line of demarcation between growth rings. Vessels plugged at intervals with dark red gum. Rays mostly 3-5 cells wide, occasionally uniseriate; few to 100 cells high; producing fine but con- spicuous “‘silver grain” on radial surface. Wood moderately heavy, hard, and strong. ECONOMIC WOODS OF THE UNITED STATES 99 b on a on Black Cherry. Prunus serotina Ehrh. (C, N, 8). Color light brown tinged with red to decid- edly reddish. Pores not crowded, fairly evenly distributed; solitary or in radial groups of 2-3. Rays with considerable red color; homogeneous. Grain often curly, “landscape,” or ‘‘bird’s-eye.”” Maple. a® Part of the rays comparatively large, 5-7 cells wide, broader than the pores; high, conspicuous. Intermediate rays mostly uniseriate. Pith flecks rare. Growth rings very distinct. Wood very heavy, hard, and strong. Sugar Maple. Acer saccharum Marsh. (N, C); Black Maple. migrum Michx. (N, C). b® With less variation in size of rays, the large ones not as broad as the pores; low, inconspicuous; few uniseriate rays. Growth rings often indistinct. a’ Color deep and rich. Pith flecks un- common. Wood fairly heavy, hard and strong. Wood elements not in tier-like arrangement. Vessels without spirals; perforations scalari- form; often with scalariform bordered pits. Rays light red or pink in color; hetero- geneous. Color pale reddish brown or pink- ish, sometimes with greenish hue. Wood very heavy, hard and tough. Dogwood. a® Rays 1-7 cells wide, few to 80 cells high. Cornus florida L. (N, C, 8). b® Rays smaller, 1-4 cells wide, few to 40 cells high. C. nuttallii Aud. (P). b> Wood elements (except rays) in tier-like arrangement, producing somewhat indistinct cross-markings on longitudinal surface. Ves- sels with spirals; perforations mostly simple; bordered pits not scalariform. Rays color- less, widely variable in size; small rays uni- seriate, 10-15 cells high; large rays, 3-5 cells wide, 50-100 cells high; homogeneous. Color light brown to nearly white. Wood light, soft, compact, moderately strong. Basswood.” Tilia americana L. (N, C), pubescens Ait. (S, C), heterophylla Vent. (A, C, §). b? Rays distinct; fairly uniform in width, 1-3-seriate. a’ Wood _ with straight grain, usually li easy to work, Wood fibres with rather thin walls, usually rounded; not in radial rows. Pores crowded; tyloses absent. Outer limit of growth ring composed of 2-4 rows of tangentially flattened wood-parenchyma fibres with very thick radial walls. Rays heterogeneous. a! Vessels with round or elliptical bordered pits; without spirals. Pores rarely in radial groups. Rays mostly 3-seriate, few to 60, mostly 20-40, cells high. Texture fine. Color variable from deep _iri ent t e_more yal- lowish brown; often striped. Yellow Poplar or ECONOMIC WOODS OF THE UNITED STATES 101 Tulip-tree. Liriodendron tulipifera L. (C, N) (Plate VI, Figs. 2, 4).* b‘ Vessels with abundant scalariform bordered pits (Plate VI, Fig. 3); with spirals, though often indistinct. Pores often in radial groups of 3-8. a> Rays crowded on cross section, conspicuous; 2-3-seriate, mostly 50-100 cells high. Pores very crowded. Texture coarse. Color light brown. —SBweet Bay. Magnolia glauca L. (8). b® Rays not crowded on cross section, incon- spicuous; nearly always biseriate and usu- ally 10-15 cells high. Pores moderately crowded. Texture fine. Color usually as in Itriodendron. Cucumber Tree. JM. acuminata L. (C, A) (Plate VI, Fig. 3). b? Wood with cross or interlocked grain, _rather heavy, moderately hard, diticutt to work; fine- textured. Wood fibres with thick walls, mostly square; in rather definite radial rows. Pores very numerous, uniformly distributed. Vessels rather sparsely pitted, often with scalariform bordered pits; spirals confined to constricted ends of segments, inconspicuous; tyloses present. Wood-parenchyma fibres few, scattered. Rays heterogeneous; very fine, 1—2-seriate, few to 30 cells high; resinous. Color reddish brown, usually with irregular dark streaks producing ‘‘watered”’ effect on smooth longitudinal surface. Red or Sweet Gum. Liquidambar styraciflua L. (C, 8) (Plate VI, Fig. 1).” c? Rays mostly indistinct to unaided eye, variable, 1—7- seriate. a? Pores comparatively few, widely variable in size, mostly In irregularly branching radial lines; near periphery of growth ring minute and in groups which appear to unaided eye as white dots. Ves- sels with numerous, rather large bordered pits; 102 ECONOMIC WOODS OF THE UNITED STATES b? with spirals; perforations simple. Rays 1-2, occa- sionally 3, seriate; few to 20, occasionally 40, cells high. Wood parenchyma in indistinct tan- gential lines barely visible with lens. Growth rings sinuous, quite distinct. Color light brown; Sapwood with pinkish hue. Wood very_heav hard, tough, difficult to split. Hornbeam. Osirya virginiana Koch. (N, C) (Plate V, Fig. 6). Pores numerous, fairly uniform in size and dis- tribution throughout growth ring, solitary or in adial groups of 2-6. Vessels without spirals; erforation scalariform. Rays variable. Growth ings regular in outline. * Wood _straight-grained, fissile, easy to work. Growth rings usually distinct. Vessels densely pitted with extremely small bordered pits with slit-like openings. Rays homogeneous. Wood -parenchyma scattered, sometimes in broken tangential lines in outer late wood. a> Rays 1—5-seriate, occasionally wider. Pores usually distinct _to unaided eye. a° Wood heavy, hard, and strong. Pores moderately abundant. Wood fibres with thick walls. Rays widest of genus, deeply colored. Pith flecks rare. Color brown tinged with red, often deep and hand- some. Sweet, Black, or Cherry Birch. Betula lenta L. (N, C) (Plate V, Fig. 5). b® Wood rather light and soft, moderately strong. Pores very numerous, larger than in preceding. Wood fibres with rather thin walls. Pith flecks common. Color brown. Red or River Birch. B. migra L. (8, C, N). b’ Rays 1-2, sometimes 3, pope Pores very small Pndlet ick tou a5 Wood_rather heavy, oT eae strong. Pores moderately abundant. Sapwood thin, light brown or yellowish. Pith ECONOMIC WOODS OF THE UNITED STATES 103 flecks rare. Yellow Birch. 8B. lutea Michx. f. (N, C). b® Wood light and_ soft, not_strong. _Sap- woog thick, white. Pith flecks usually abundant. Paper Birch. B. papyrifera Marsh. (N, Rn, Pn). Gray Birch. populifolia Marsh. (N). b* Wood cross-grained, tough to split, difficult to work. Growth rings usually indistinct. Ves- sels sparsely to densely pitted with moderately large bordered pits sometimes scalariform. Rays heterogeneous; 1-5 cells wide, few to 40 cells high. Wood parenchyma mostly around vessels, not in tangential lines. Color brown to nearly white. a> Rays mostly 1—-2-seriate (sometimes wider). Pores numerous, usually evenly distributed. a® Pores of medium size. Wood fibres with rather thin walls and large lumina. Wood light. (sp. gr., .54), soft, not strong. Tupelo. Nyssa aquatica L. (8, C).*? b® Pores small. Wood fibres with thick walls and small lumina. Wood com- paratively heavy (sp. gr., .64), hard and strong. Black Gum. JN. sylvatica Marsh. (C, N, 8). b> Rays mostly 3—-4-seriate. Pores compar- atively large, not very numerous, unevenly distributed. Wood fibres with thin walls and large lumina. Wood light (sp. gr., .53), soft, not strong. Sour Tupelo. N. ogeche Marsh. (S). d? Rays very fine, indistinct, uniseriate. a? Growth rings limited by 1-2 rows of thin wood- parenchyma fibres. Pores very numerous. Ves- sels densely pitted; perforations simple. Wood light and soft. at Rays distinct under lens, mostly 10-12 cells high. Pores minute, invisible to unaided eye, 104 ECONOMIC WOODS OF THE UNITED STATES mostly solitary, uniformly distributed. Vessels with spirals. Color pale yellow to nearly white. Lustrous. Texture very fine and uni- form. Grain often wavy and somewhat inter- locked. a> Wood elements (including rays) in tier-like arrangement, producing very distinct trans- verse lines on longitudinal surface. Buckeye. Zisculus octandra Marsh. (C).” b> Wood elements not in tier-like arrangement. Ohio Buckeye. A. glabra Willd. (C) (Plate VI, Figs. 5, 6); California Buckeye. califor- nica Nutt. (Ps). b‘ Rays indistinct under lens; 1-25, mostly 10-15, cells high. ores variable; in short radial groups. Vessels without spirals. Grain usually straight. a> Rays heterogeneous. Pores minute, invis- ible to unaided eye. Color pale reddish brown. Lustre dull. Black Willow. Salix nigra Marsh. (N, 8, C, Rs, Ps). b> Rays homogeneous. a® Pores minute, invisible without lens. Texture very fine. Lustre silky. Color light brown to silvery white. Aspen. Populus tremuloides Michx. (N, C, R, P).* Large Tooth Aspen. grandidentata Michx. (N, C). b® Pores small to minute, those in early wood usually visible to unaided eye. Texture coarse. Lustre dull. Color pale, dull “Brown, or grayish brows. Cottonwood. “P. heterophylla L. (8, C), trichocarpa T. & G. (P), deltoides Marsh. (N, C,8, R). ECONOMIC WOODS OF THE UNITED STATES 105 REFERENCES 1Pine: Baitey, Irvine W.: The Structure of the Wood in the Pinew. Bot. Gaz., Vol. XLVIII, July 1909, pp. 47-55. Baitzy, Irvine W.: Anatomical Characters in the Evolution of Pinus. Am. Naturalist, Vol. XLIV, May 1909, pp. 284-293. Hau, Wituiam L., anp Maxwe.u, Hv.: Uses of the Commercial Woods of the United States, II. Pines. Bul. 99, U. 8. Forest Service, 1911. BURGERSTEIN, ALFRED: Vergleichende anatomische Untersuchungen des Fichten- und Larchenholzes. Denkschrift f. kaiserl. Acad. wissensch. Math.- Natur. Classe, Vol. LIX, No. 6, 1894, pp. 214-215. 2"White Pine Group: Rocxwe.u, F. I.: The White Pines of Montana and Idaho—Their Dis- tribution, Quality and Uses. For. Quarterly, Vol. IX, No. 2, 1911, pp. 219-231. 3Pinus strobus: Spaupine, V. M.: The White Pine. Bul. 22, U.S. Div. Forestry, 1899. {Pinus lambertiana: Coorrr, ALBERT W.: Sugar Pine and Western Yellow Pine in California. Bul. 69, U.S. Forest Service, 1906. 5Pinus edulis: Puuuirs, F. J.: A Study of Pifion Pine. Bot. Gaz., Vol. XLVIII, Sept. 1909, pp. 216-223. Heuser, A. A.: The Nut Pine. Muhlenbergia, Vol. V, 1909, pp. 31-35. ®Southern Pines: Frernow, B. E.: Southern Pine: Mechanical and Physical Properties. Cir. 12, U. 8. Div. Forestry, 1896. Mour, CuHares, anD Roru, Firrsert: The Timber Pines of the Southern United States, together with a Discussion of the Structures of their Wood. Bul. 13 (rev. ed.), U. 8. Div. Forestry, 1897. Betts, H. §.: Properties and Uses of the Southern Pines. Cir. 164, U.S. Forest Service, 1909. 7Pinus palustris: Frernow, B. E.: Timber Physics, Part II, Results of Investigations on Longleaf Pine. Bul. 8, U.S. Div. Forestry, 1893. Birrine, Katuerine G.: The Histological Difference between Pinus taeda and Pinus palustris. Proc. Ind. Acad. Sci., Indianapolis, Ind., 1908, pp. 127-129. 8Pinus teda: Zon, RapHazE: Loblolly Pine in Eastern Texas. Bul. 64, U. S. Forest Service, 1905. Hatt, W. Kenpricx: Second Progress Report on the Strength of Struc- tural Timber. Cir. 115, U. 8. Forest Service, 1907. Pinus radiata: ALBERT, F.: El Pino de Monterei, Pinus insignus o mejor Pinus radiata. Santiago de Chili Min. Indust., 1908. 106 ECONOMIC WOODS OF THE UNITED STATES Pinus sabiniana: Suinn, CHarxtes H.: Economic Possibilities of Pinus sabiniana. Proc. Soc. Am. Foresters, Vol. VI, No. 1, 1911, pp. 68-77. UPinus virginiana: Sterrert, W. D.: Scrub Pine. Bul. 94, U. S. Forest Service, 1911. Pinus ponderosa: Cooprr, ALBERT W.: Sugar Pine and Western Yellow Pine in California. Bul. 69, U. S. Forest Service, 1906. Woousey, Tueopore S., Jr.: Western Yellow Pine in Arizona and New Mexico. Bul. 101, U. 8. Forest Service, 1911. BPseudotsuga taxifolia: Curve, McGarvey, AND Knapp, J. B.: Properties and Uses of Douglas Fir. Bul. 88, U. S. Forest Service, 1911. Frotsineuam, E. H.: Douglas Fir: A Study of the Pacific Coast and Rocky Mountain Forms. Cir. 150, U. 8. Forest Service. “Spruce: Hopson, E. R., anp Foster, J. H.: Engelmann Spruce in the Rocky Mountains. Cir. 170, U.S. Forest Service, Washington, D. C., 1910. Jerrrey, Epwarp C.: The Comparative Anatomy and Phylogeny of the Coniferales, Part II, Abietinee. Mem. Boston Soc. Nat. History, Vol. VI, No. 1, Boston, 1905. Bastin, E. S., AND Trimpie, H.: A Contribution to the Knowledge of North American Conifere. Amer. Journal Pharm., Vol. LXVIII, No. 8, 1896, pp. 409-422. Sequoia: Hau, Witu1aM R., anp Maxwetu, Hu.: Uses of Commercial Woods of the United States. I. Cedars, Cypresses, and Sequoias. Bul. 95, U.S. Forest Service, 1911, pp. 57-62. Jerrrey, Epwarp C.: The Comparative Anatomy and Phylogeny of the Coniferales. Part I, The Genus Sequoia. Mem. Boston Soc. Nat. History, Vol. V, No. 10, pp. 441-459. Jerrrey, Epwarp C.: A Fossil Sequoia from the Sierra Nevada. Bot. Gaz., Vol. XXXVIII, No. 5, pp. 321-332. Sequoia washingtoniana: A Short Account of the Big Trees of California. Bul. 28, U. 8S. Div. Forestry, 1910. “Sequoia sempervirens: Fisuer, Ricwarp T., et au: The Redwood. Bul. 38, U.S. Bu. Forestry, 1903. Gorpon, Marsorie: Ray Tracheids in Sequoia sempervirens. New Phy- tologist, Vol. XI, No. 1, Jan. 1912, pp. 1-7. 187ibocedrus decurrens: Hau anp MaxweEtw: loc. cit., pp. 31-33. wJuniper: Cedar: Hay anp MAxwELL: loc. cit., pp. 11-31. ECONOMIC WOODS OF THE UNITED STATES 107 Juniperus virginiana: ime Cuar.es: Notes on the Red Cedar. Bul. 31, U. 8. Bu. Forestry, Waitt, L. L.: Production of Red Cedar for Pencil Wood. Cir. 102, U.S. Forest Service, 1907. 1T suga heterophylla: oor. Epwarp T.: The Western Hemlock. Bul. 33, U. 8. Bu. Forestry, 1902. Oax.ear, Howarp B.: Wood-using Industries of Oregon. Pub. by Oregon Conservation Assn., Portland, Ore., 1911, pp. 29-30. Fir: Tuompson, W. P.: Ray Tracheids in Abies. Bot. Gazette, Vol. LIII, No. 4, Apr. 1912, pp. 331-338. Bastin, E. 8., anD Trimpiz, H.: A Contribution to the Knowledge of the North American Coniferee. Amer. Journal Pharm., Vol. LXVIII, No. 10, 1896, pp. 554-566. 8Taxodium distichum: Rots, Fiupert: Progress in Timber Physics: Bald Cypress (Taxodium distichum). Cir. 19, U. 8. Div. Forestry, 1898. Haun anD MaxweE tu: loc. cit., pp. 41-47. 4Thuya plicata: Haut anp MaxweE.. loc. cit., pp. 36-41. %Chamecyparis nootkatensis: Hau anp MaxweE..: loc. cit., pp. 35-36. 6Chamecyparis lawsoniana: Hatt anp MaxweE Lu: loc. cit., pp. 33-35. 71Chamecyparis thyoides: Hau anp MaxweEL: loc. cit., pp. 12-16. 2Thuya occidentalis: . Hau anpD MaxweE wu: loc. cit., pp. 16-19. Castanea dentata: Asner, W. W.: Chestnut in Tennessee. Bul. 10, B, Tenn. Geol. Survey, Nashville, 1912. Zon, RapHaEu: Chestnut in Southern Maryland. Bul. 53, U. S. Bu. Forestry, 1904. Lavage, J. B.: Le Chataignier. Paris, 1906. 300 ak: _ Supworts, Georcz B., anD MELL, C. D.: The Identification of Important North American Oak Woods. Bul. 102, U.S. Forest Service, 1911. Bartzy, Irvine W.: Notes on the Wood Structure of Betulaceer and 'Fagacee. Forestry Quarterly, Vol. VIII, No. 2, 1910. Bartey, Irvine W.: On the Origin of the Broad Ray in Quercus. Bot. Gaz., Vol. XLIX, No. 3, March 1910, pp. 161-167. Bartey, Irvine W.: Reversionary Characters of Traumatic Oak Woods. Bot. Gaz., Vol. L, No. 5, Nov. 1910, pp. 374-380. : Groom, Percy: The Evolution of the Annual Ring and Medullary Rays of Quercus. Annals of Botany, Vol. XXV, Oct. 1911, pp. 983-1004. 108 ECONOMIC WOODS OF THE UNITED STATES 2 JOHANNES: Ueber die Anatomie des Eichenholzes. Berlin, Quercus alba: GREELEY, W. B., anp AsHE, W. W.: White Oak in the Southern Appa- lachians. Cir. 105, U. S. Forest Service, 1907. 82Quercus prinus: Foster, H. D., anp Ase, W. W.: Chestnut Oak in the Southern Appa- Jachians. Cir. 135, U. 8. Forest Service, 1908. 8Catalpa speciosa: Hatt, Wittiam L.: The Hardy Catalpa. Bul. 37, U.S. Bu. Forestry, 1902. Recorp, Samvuru J.: The Hardy Catalpa. Pub. 22, Dept. of Botany, Wabash College, Crawfordsville, Ind., 1906. Roserts, H. F.: The Hardy Catalpa. Bul. No. 108, Exp. Sta., Kansas State Agri. Coll., Manhattan, Kans., 1902. “4Sassafras sassafras: Knosiatcu, E.: Anatomie des Holzes der Laurineen. Flora, 1888, Nos. 22-26, pp. 339-400. See also Bot. Centralblatt, Vol. XX XIX, p. 125. Tozylon pomiferum: MaxweE.., Hv.: Utilization of Osage Orange. Pub. by Farm Wagon Dept., Natl. Implement and Vehicle Assn., U. 8. A., 1911. Supworts, GeorceE B., anp MEL, Cuayton D.: Fustic Wood: Its Sub- stitutes and Adulterants. Cir. 184, U. 8. Forest Service, 1911, pp. 8-9. Robinia pseudacacia: JarmnscH, Tu.: Zur Anatomie einiger Leguminosenhélzer. Ber. d. deutschen Bot. Gesellschaft, Vol. II, Berlin, 1884. Saupr, K. Autwin: Der Anatomische Bau des Holzes der Leguminosen und sein Systematischenwerth. Regensburg, 1887. Diospyros virginiana: Moutscu, H.: Vergleichende Anatomie des Holzes der Ebenaceen und ihrer Verwandten. Sitzb. der kaiserlichen Akademie der Wissenschaft, Vol. LXXX, Part I, Wien, 1879. 38H ickory: Borsen, ANTON T., anp Newuin, J. A.: The Commercial Hickories. Bul. 80, U. S. Forest Service, 1910. Hatcuo, Cuarsss F.: Manufacture and Utilization of Hickory, 1911. Cir. 187, U. 8. Forest Service, 1911. "Hvergreen Oak Group: Bai.tey, Invinac W.: Notes on the Wood Structure of the Betulacee and Fagacee. For. Quarterly, Vol. VIII, No. 2, 1910. *9Quercus densiflora: Jerson, Wituis Linn, anp Berts, H. §.: California Tanbark Oak. Bul. 75, U. 8. Forest Service, 1911. A Swietenia mahagoni: Supworts, Grorce B., anp Meu, Cuayron D.: “Colombian Mahog- any’; Its Characteristics and Its Use as a Substitute for True Mahogany. Cir. 185, U. 8. Forest Service, 1911. ECONOMIC WOODS OF THE UNITED STATES 109 Buscu, P.: The Commercial Mahoganies. Tropenpflanzen, Vol. XV, No. 9, 1911, pp. 479-493. “Eucalyptus globulus: _ Berts, H’S., anp Smita, C. Srowei: Utilization of California Eucalypts. Cir. 179, U. S. Forest Service, 1910. S8Walnut: Supwortu, Grorce B., anp Meu, Cuayton D.: Identification of North American Walnut Woods. Bul. 120, U. S. Forest Service, 1912. “Carpinus caroliniana: Barter, Irvine W.: Notes on the Wood Structure of the Betulacee and Fagacee. For. Quarterly, Vol. VIII, No. 2, 1910. * Alnus oregona: BaitEey, Irvine W.: The Relation of the Leaf-Trace to the Formation o Compound Rays in the Lower Dicotyledons. Annals of Botany, Vol. XXV, an. 1911. OaxLEaF, Howarp B.: The Wood-Using Industries of Oregon. Pub. of Oregon Conservation Assn., 1911, pp. 38-39, 41. 46 Maple: Hoven, Rurs: Some Features in the Anatomy of the Sapindales. Bot. Gaz., Vol. LIII, Jan. 1912, pp. 50-57. *" Basswood: Recorp, SaMvugEL J.: Tier-like Arrangement of the Elements of_Certain Woods. Science, Vol. XXXIV, Jan. 12, 1912, pp. 75-77. Tiriodendron tulipifera: GROPPLER, Ropert: Vergleichende Anatomie des Holzes der Magnolia- ceen, Stuttgart, 1894. See also Bot. Centralblatt, Vol. LX, p. 373. 8Tiquidambar styraciflua: CHITTENDEN, ALFRED K., anD Hatt, W. Kenprick: The Red Gum. Bul. 58, U.S. Bu. Forestry, 1905. ‘ Betula papyrifera: Dana, S. T.: Paper Birch in the Northeast. Cir. 163, U.S. Forest Service, 1909. Nyssa aquatica: Hotroyp, H. B.: The Utilization of Tupelo. Cir. 40, U.S. Forest Service, 1906. Supworts, Grorce B., anp Meu, Crayton D.: Distinguishing Char- acteristics of North American Gumwoods. Bul. 103, U.S. Forest Service, 1911. Von Scurenck, Hermann: Tupelo. Southern Lumberman, Anniversary ed., 1907. 82 #sculus octandra: Recorp, SamvueE. J.: Tier-like Arrangement of the Elements of Certain Woods. Science, Vol. XXXIV, Jan. 12, 1912, pp. 75--77. 8Salix nigra: PreNnHALLOW, D. P.: A Systematic Study of the Salicacee. Am. Naturalist, Vol. XXXIX, No. 464, Aug. 1905. 110 ECONOMIC WOODS OF THE UNITED STATES ' Hoxpen, Rurs: Reduction and Reversion in the North American Salicales. Annals of Botany, Vol. XXVI, Jan. 1912, pp. 165-173. “Populus tremuloides: WEIGLE, W. G., anD Frotarncuam, E. H.: The Aspens: Their Growth and Management. Bul. 93, U.S. Forest Service, 1911. Bureerstein, A.: Diagnostische Merkmale der Markstrahlen von Popu-, lus und Salix, Ber. d. Deutschen botanischen Gesellschaft, Vol. XXIX, No. 10, 1911. Breton-Bonnakp, L,: Le Peuplier. Paris, Lucien Laveur, 1903. INDEX PAGE ABIES visas ccceiadde 23, 29, 30, 45, 64 AMADIS? 2. vac ac «asses dard weed 85 balsam és. isewnils auc wwnicecugns eles 85 CONC OR i cae aglaine sexes: 85 {LASCl eins ees vens ca ex eee wes 85 Brandis: .2s vicar sagen rey chs 85 lasiocarpa................040. 85 magnifica............ 0... eee 85 TIONS eis cee gs tad oho Masecuenine 85 Acacia homophylla......... ... 68 Acer....... 7, 27, 40, 43, 44, 47, 64, 66 macrophyllum............... 94 negundo..................0.. 99 californicum............... 99 QVM bss scan caans sons aw es 99 rubrum................... 37, 99 saccharinum............... 37,99 saccharum.............. 37, 47, 99 Acerace®........... 00502002 eee 36 Aésculus 7, 15, 22, 24, 25, 27, 40, 47, 64 californica.................. 104 GIADA. sip s-Sack oe eee ere ed 104 octandra................. 39, 104 Aggregate rays................ 26 Ailanthus...................- 7 VIER sascerarnuarsug RAG MOREA IOARS 97 AMHUS x2.c.0cideene as cee cede 7, 26, 64 oregona............... .. 65, 97 Alpine fits s)2:.2ss0 doug eeu sige eoten 85 Angiosperms.................. 6, 11 ANONBasd xcs se hees get Eete hs 8, 33 Aperture of pitcanal........... 32 Arborvit#@............0...000. 87 NSW ces ihay oaoqaemed ange) 90 ASIMING ocied cc ee aad Acie caunuen 8 ASPEN sccscacyee Gadswnerca’ 104 PAGE BALD CYPRESS................ 86 Balsam fir.................... 85 Bark iedcinieaidseaid inate oe are ey 5,8 Bars of Sanio................. 38 Basswood... 2... 0660s .se ee euss 100 Bast fibres....................8, 66 Bay oe oe tid hss hich 2 cna ean od ae 101 BeGchivis pcs 354 equa ban cdavica ce 98 Betula. .7, 10, 15, 27, 37, 43, 64, 66, 68 Veritas. sss susan d Woe Side, ae 37, 65, 102 MUGS iaeccda un ee dehex aaiad 37, 103 HIG. oon sececaesanaanes 37, 102 papyrifera................ 37, 103 populifolia................87, 108 Betulacee.................... 36 DIE TOG». 35.5: 4 Shee dawn Gao eae wow 83 BFC aa as naka en a ewalace cone Metta 102 Bitternut hickory............. 94 Black ashi. aiid ecu se cadues 91 DbinGhyrcseleeniios panaln amie 6 Re 102 cherry . 99 CUM by eave ave spam ieee x 103 loeUSti s 63355.heu Aen Ses 93 Maples. oy csgdeca dunce 99 OAK: Sa.dbSiiien i oan oennesandinbs 88 SPYUCO oo. chi etca eal eeaansccns 83 Wally. od oi eeuanatione aes 96 WIDOW i civccldinng mate ieee 2 104 BlUG GShine cea ncinceas aves 91 beech ech jactcettandorten > 97 UM 2 faa. : Ans ces ghige ace gE 96 Border of pit................. 32 Bordered pits................. 16 Boxelder...............0.0005 99 Branch wood................. 5 Broad rays................... 26 Broadleaf woods........ .. 4, 17, 87 111 112 INDEX PAGE PAGE Bur Oak: .cissigneaeeie ha omnes 88 Common catalpa.............. 92 Butternut............... 0008s 97 Companion cells............... 8 Buttonball................0.. 98 Condalia ferrea............... 50 Conductivity of wood.......... 62 CHISALPINA.......0..0.0 0000000 ee 65 «Conifere...........5 0.000004. 6 Cesalpiner...............0000. 30 Coniferous woods............. 7,78 Calcium oxalate crystals....... 21 Conjugate cells................ 25 California buckeye............ 104: CORK cso ccioadien tomes eee 9,10 NUMER sz sonido ee ex alee 84 cambium.................-- 9 Cambium................... 11,12 Comus. . 25.04 oe eee nea neat aw 7,15 Camphor trees..............00. 68 Moria: wacge many ras ees 100 Camphora glanduliferum....... 68 Null; «cose ee geeky ets 100 Canal of pit.................. 32. - COrtex sass cual sissirely aspen e406 8 Carbonate of lime in vessels.... 15 Cottonwood.................. 104 Carpinus............... 9,26,41,97 Cowoak............... eae tes 88 Case-hardening............... 58: . Crystals:s.2iaesedesecdese se4 9, 21 Castanea........... 40, 47,48, 68,69 Cuban pine................... 80 dentata.............20..00. 87 Cucumber tree................ 101 pumila. esleace dna enaees 87 Castanopsis chrysophylla....... 87 DENSITY OF WOOD............. 49 Catalpa............... 44, 64, 68,92 Dentate walls of ray tracheids.. 27 Catalan Wisk oosae amen 92 Dicotyledons SPCCIOSA sie pear age seis edie 4 92 7, 13, 14, 21, 30, 41, 61, 87 Cedaryesvevaccatanece nah eens 84 Diffuse-porous woods......... 16, 43 CliNs piv den cose eo eena eases 90 Diospyros..............0000e 21, 22 Celtisicnwssstesagesee? 25, 27, 44, 45 virginiana.............. 39, 64, 94 mississippiensis.............. 89 Dipterocarper................ 30 occidentalis................. 89 Dogwood................0000- 100 Cercidium.................... 67 Douglas fir................05- 82 Chamecyparis................ 64 DrimyS nna oesadeninwsercnwe’s 14 lawsoniana.......... 67, 68, 69,86 Drying of wood............... 53 nootkatensis............... 68,86 Dryobalanus camphora........ 68 thyoides................... 68,87 Durand oak.................. 88 Checking of wood............. 56 Dyewoods................005. 65 Cherry's: soniee 3s a4 eeey cele ect 99 birchiacs+ + hs wistesteneae a acces oy 102 EasTERN HEMLOCK............ 85 Chestnut...............0 00005 BC DIN osc nicest ada idee Sans eke Widen 89 Dale’. hij kannada dlaniia Bied ogi 88 Epidermis...................- 8 Chinquapin.................0. 87 Epithelial cells................ 22 chestnut................... 87 Epithelium................... 29 Cinnamomum camphora....... 68 Eucalyptus............... 47, 57, 96 Cladrastis lutea.............. 64,65 Evergreen oaks............... 95 Clorophora tinctoria........... 65 Coffee tree................0.. 93! PAGARA ss vsweawgeees ras pee ye 66 Color of wood.............+.4. 64 Fagus....... 7, 9, 26, 43, 44, 47, 66, 98 INDEX 113 PAGE PAGE False rays. ..issscesssseasiees 26 Hicoria aquatica.............. 94 False rings............0.0.00. 41 Glabrae i. cciactia sn seuree had ea 94 Fascicular cambium........... 12 laciniosa.................. 10, 94 BAbreS iiiccasiccis soda ee b hee oes 13, 88 minima...... uaenlee ast meee aals 94 Fibre-saturation point......... 54 myristiceformis............. 94 Fibrous elements of wood...... 13 OVALE. gies cea dopa eane awe 94 Fibro-vascular bundles......... WAZ OUY tase sc cctvghatane Yoo esa ee 98 Foxtail pines.................. 79 Homogeneous rays............ 25 Fraxinus...7, 25, 27, 40, 44, 47, 48, 64 WOOK cist eer eaerewan TS AMETICANA..... 060 ca pee es 22,91 Honey locust................. 93 caroliniana................. 90 ‘“Honeycombed” wood......... 58 lanceolata.................. 91 MHornbeam.................... 102 DIU Ay eiahe ears Hes ate eee 22,91 MHygroscopicity of wood........ 59 OPePONAases sees ee cee dee RE 91 pennsylvanica............... 91 Ivex............... 10, 45, 64, 65, 98 quadrangulata.............. 91 Incense cedar................. 84 Fundamental meristem......... 11 Indian sandalwood............ 68 Fusiform rays...............5 25,29 Inter-fascicular cambium....... 12 Us biG sins, foc nad aiek baancn ht Beater od 65 Intermediate wood fibres....... 25 GLEDITSIA: . 2 cis ca aiee eae kanes 15,93 JUGLANS............. 7, 8, 15, 21, 65 GIOSSiasere nes aeeratsaea chews 66 cinerea........ 2... eee eee 97 GYAIN cio ca oe reied emp ooawees 46 MPT cows aeo acer aidan aee 66, 96 Gray birch................... 103. Juniper...................04. 84 Green ash.............-...025. 91 Juniperus.10, 22, 41, 44, 45, 47, 64, Growth rings................ 16, 40 68 Guaiacum............. 15, 50, 66, 96 barbadensis................. 84 Gum in vessels................ 15 CalifOrMicas..: ccc cwwvwrs ssa os 84 Gymnocladus........ 7, 15, 44, 47, 93 monosperma................ 84 Gymnosperms, 6, 7, 11, 13, 16, 25, 31, occidentalis................. 84 38, 40, 43, 61, 78 pachyphloa................ 84 scopulorum.............-.-. 84 HACKBERRY..........--.--00- 89 utahensis................... 84 Hematoxylon campechianum... 65 virginiana........... 66, 67, 68, 84 Hard pine.................0.. 80 Hardwoods.............-2+.-+- 7,87 KENTUCKY COFFEE TREE....... 93 Hardy catalpa................ 92 Key to the economic woods cf Heartwood................ 6, 44, 64 the United States........... 78 Hemlock................-045 32,80) KKMOtS sas.2ncccnds Gon dees we eek 48 Heterogeneous rays..........+ 24, 25 WOOdS: iid veen gia vernens pee 87 DARK. 2co ae eaten ces Gees 82 Hickory: cvieeerinena yses eeues 94 Large tooth aspen............. 104 Hickory elm.................. OO: ALIKE ted oaimupeitos wlidins 25, 29, 31, 36 Hicoria............. 2, 21, 22, 44, 66 americana................. 46, 81 BMD Bisse cede. Beestonauisnans wma 94 occidentalis................. 82 114 INDEX PAGE PAGE Leitneria floridana............ 31,50 Nyssa............... 8, 45, 47, 57, 64 Libocedrus............ 22, 68, 69, 84 aquatica .................. 103 Lignumvite.................. 96 ogeche.................000. 103 Limiting membrane of pit...... 33 BYIWALICA scans See ens SSS 24, 103 Liquidambar 14, 19, 33, 40, 47, 57,64, 101 Oak...........0... cece eee 16, 87 Liriodendron Odor of wood................. 67 8, 10, 15, 22, 35, 43, 45, 64,101 Ohio buckeye................. 104 List of. general classifications of Old fustic.................... 65 WOO xo Aina cvandunesainloneaamancee s 69 Oregon ash................... 91 List of publications dealing with Osage orange............... . 92 the characteristics of woods.. 71 Ostrya virginiana.............. 102 List of publications dealing with Overcup oak.................. 88 the uses of American woods.. 76 List of references to species in PARENCHYMA............. 13, 25, 27 KOViswaers 6 ae rues exe baaeed 105 Parenchymatous elements of Live Oak: <2. .c)o 4233s een oes 16, 95 WOO ss4s re55 69 eee aee 13 Loblolly pine................. 80 tracheids................. 17, 27 Longleaf pine................. 80 Parkinsonia................... 67 Loose knots..............-... 48 Pecan hickory................ 94 Lowland fir................... 85 Penetrability of wood.......... 60 Lustre........... petites ae BS 66 Perforations of tracheids....... 18 of vessels........ 0 ....... 14, 15 MAcERATION OF WOOD......... 4 Perieyclesnccss cece doeser sas 8 Magnolia............ 8, 15, 22,35,40 Persimmon................... 94 acuminata. .,00.cssKieeen ane 101. Phelloderm................... 9 ClAUCA ea coke piensa oles 101 Phellogen.................. 9 Magnoliacee................. 14,33 Phloem: <2 seseen¢je25ncKe 588 8,11 Mahogany.................... 95 parenchyma................ 8 Maples casecraans adnueneece 63,99 Physical properties of wood..... 2,5 Medullary ray............... 21,23 Picea........ 25, 27, 29, 31, 36, 45, 64 SPOtSen Mewes saieantoine xe nels 36 canadensis.................. 82 Mockernut hickory............ 94 WANIANA, «2 seve care eed poten He 83 Monocotyledons............... 7 rubens.................20-. 83 Momus cciee ie tee nins 44, 64, 65, 93 sitchensis................... 88 Mucilage sacs................. 9 Pignut hickory................ 94 Mulberry 2 o2ssied secs ayseasa 93 Pinjoakes ss ons Ae nee ines werd aees 88 Pine eds sone tyes Oe sae TREES 78 NEEDLE-LEAF WOODS.......... 7 ~ Pinus 2, 10, 23, 25, 27, 28, 31, 36, 67, Noble fir................200., 85 68, 69 Non-porous woods............. 78 albicaulis................... 79 Norway pine.................. 80 BISA c5 hc tee Seda Bae 79 Nut pine..................... 79 E31 7.0) 0) (ct: nn 81 INUtMER Ys ugyeuswadeea wet de ged 84 attenuata.................. 81 DICKOTYe:s. saricuass Seeee dn 4 94 balfouriana................. 79 INDEX 115 PAGE PAGE Pinus cembroides............. 79 Postoaky.. cecucccessex uses oe 88 chihuahuana............... 81 Primary meristem............. 11 ClAUSBi: 22 es dgods pave eats au 81 Phloems. 0.6 6c cecenarcae EL Coulteri.. 2... eee eee 81 FAS! Grad sua debian debe 23 divaricata.................. 81 Wall Arc icarieNi ae eanye ands 31, 61 echinata..............00.... 80 WOO: na peer hewge a eae eae Sue 11 Cds cls aloe can 26,79 Primordial meristem........... 11 AOR, 5 cs sco cee we ace oe eae 79 Procambium strands........... 11 PALS sce aes ae es beens Se 81 Procumbent,ray cells.......... 24 heterophylla............... 45,80 Prosopis..................15, 64, 65 lambertiana.............. ... 79 Protoderm...... ............. 11 monophylla................. 79 Proto-phloem................. 11 monticola................. 65,79 Proto-xylem.................. ll murrayana................ 38,8 Prunusvesscersn vive rkadeog sane A4T palustris... .7, 44, 48, 53, 55, 69, 80 SCTOUNAs secs vies nee nas vee 99 ponderosa.............. 30, 31,81 Pseudotsuga pungens.................... 81 7, 16, 23, 25, 27, 29, 31, 36, 48 quadrifolia................. 79 macrocarpa..........-....-- 82 radiata....................2 81 taxOlidis< 2a buna. e-AOMOy Sheep Daw Of Contractsisenccirs co pedi sao Wena ended s eaves as et Sh ta 8vo, Law of Operations Preliminary to Construction in Engineering and PICIUCE TIPE 5 soetacs dasa 64 CRESS 4h Pees Se Pee eek ee Wilson’s Air Conditioning... 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