oe She RATS ne Te ee a ay RE age EN eo! eG oo = See vii) —_ Regret ¥ es rire Settee te AOC Brac Seas xe I einen Wie SS SS Shinn Sater Sires blaring Serie ‘ ss eat Si elias ante anaes ee aoe cae eae = ee te erie 2s eee Raper ia > eek SS COS estate ante tea eee eet eeeiees Sor oer Sarco Cemeeeneerieitrete Ne Sethe eer enon Sab enele wees speireieictoeintens ie ane Cater osir ear lesieirs a aortcrl Saat a erected iy a ic pipleirisehoreongs eee 5 rae eee “a Geeta Te tet et ee eee Cer tein ere eaters Sots area , oe oa ee Sp eariteeeanae BS fe alin Clee es ESNIPS OES Sos baled Sore eet eae e Ee eee ite o 5 ers Santi feet ee Aap ae se IO nF ALBERT R. MANN LIBRARY AT CORNELL UNIVERSITY wing Introductory Leeture, July &, 1900. Plant ecology is really the science of plant house-keeping or the study of the relations of plants or plant organs to isle environments. Parts of plants, individual plants, and groups of plants have distinct relations to their environment. Morphology of plants tries to answer the question'what”' Physiology, the question "how?" Ecology, the question "why?" Heology presipposes elasticity in the plant organisn. Plants and their organs are adapted to, or working towards, adaptation to their environment. All things in nature have a meaning. we have a right to the question why. Plants may hecome less adapted to environment if the latter is changing. Rudimentary organs are less common in plants than in aniwials. Variations may be looked for along tiuree lines. l.in different species. Finding intermediate links. 2.In separate individuals of the same species. 3,In the same individual. The theory of meiccizis hypothesis calls for every possible explanation that will account for the phenomenon and then finding as many phenomena as possible which will not accord with the theory. The remaining theories will form a working hypothesis, GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. ithaca: Ns KY vg ssccecssceveeseeconpeiee hates) iors 290... Lecture 2, July 6, 1900, Plant Functions. Normal plants if there are such ; typical plants, a better name. Plant function includes nutrition, conduction, photosynthesis conduction, storage, respiration, digestion, transpiration, secretion and excretion, and movement. 1. Nutritive function. The five most important substances absorbed are 0, COa,H,0O, organic and inorganic substances ; the first two are taken in through the stomates, the others by the root- hairs from the soil. Exceptions are found in submerged and desert plants. The former take theirs in from the H,O through the skin, the latter from the air. 2. Conduction of raw material. O and COg are in the leaves where they can be used. The others must be carried through the tubes. 3. Photo-synthesis. Carboh assimilation is a better term. COs + H,O = CH,O + OQ, or and oxygen. CH30 is a carbohydrate — Proteids introduce a new element N. Some N may pass through the stomata but not much. 4. Conduction to place of use. Xylem eélls carry water. Sieve tubes of ploem carry the proteids. Sugar can be more’ easily carried since it passes through any part by osmosis. Starch can only be carried as starch in the milky juice of plants as in Buphoebia. The eross section of 4 pumpkin shows sieve tubes with a viscovs fluid. The development of the flower is complex, since GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, N. Y., 3 the unmanafactured material must be carried to the leaves and after being chanced, must be taken to the flower. 5. Storage. Perennial plants show storage to the best advantuce. Magnay is an extreme example. Proteids are stored up in seeds, and carbohydrates in almost all parts of the plant. Storage of water is greatest in succulent plants and very common in all plants, especiali:; those which grow in the desert. 6. Digestion is hardly important to be classed wnder a distinct head since it is confined to carnivorous plants. 7. Respiration is one sort of oxidation. Tne external manifesta- tion is just the reverse of protoszyntax. The latter throws off O while respiration gives off CO. 8. Transpiration or the giving off H,0, is of great importance ; it is evaporation and is modified by the plant. Warming attributes most things to it. It was formerly supposed that all the water was raised by the roots, but this view is thought now to he incorrect. 9. Secretion and Excretion. By excretion 0 is given off in photosyntax, HyO by transpiration. All secretions and excretiors are not necessarily given off through glands. Plants have organs of secretion less full: developed than animals, yet their organs meet their nesds since plants take in less unnecessary materials than animals, and consequentiy have less waste. Examples of excretion are tannin, resins, gums and oils. Its function determines the nature of a gland. A secretion is a product which has some use in the plant organism. Some secretions GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Yo teces sons ee ee 4 are excretions. Glands ,ay be external or internal. Dots on orange rind and spots on mint are external glands. 9. Movement. Lower plants like Algae have much movement. nigher plants movement is confined to the leaves. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthatta,, Bh Yo ypocnccaze ee YO... Lecture 3, July 7, Light. The influence of light on vegetation is one of the most important factors in plant life. Light is absolutely necessary to all green plants, indirectly to all life. If things are parasites or saprophytes, they are indirestly dependent. Chlorophyli depends on light. Plants kept in the dark do not develop it and even lose what they had, as in the bleaching of celery. Growth independent of sunlight is the result of stored-up food. A potato will grow in a dark cellar. Fungi have been found growing in caves on bits of tallow, droppings from the miners’ candles. Plant gwowth is influenced not only by intensity but also by duration of light. Oats will ripen more quickly in some northern sections than in those lying further south. The reason for this is supposed to be partly the continued periods of light in the northern regions... Other colors, especially in autumn, are associated with sunlight. This coloring is usually found on the upper side of the leaf or on the under side if that has been exposed to the direct sunlight. The opening and closing of flowers is also influenced by the Light. Other factors also help to produce this effect. Too much light injures the chlorophyll. Plant forms are greatly influenced by the intensity and duration GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, Ni Yuji ccc oo EGO. 6 of light. Trees of some species will have different shapes when standing alone or in forests, Many plants may be divided into heliophilous (sun-loving} am heliophobous (shade-loving) as most forest trees. If we arrange forest trees according to their need of light, we would probably have an arrangement like the following :- larch, birch, aspen, pine, linden, oak, beech. If a beech-nut £an sprout ina beech forest while an oak canuot, the final stage of our forests will be beech forests. All plants do not come under these divisions. Poison ivy has a wide range. A plant which adapts itself to a large habitat is plastic in its habits. Heat. Heat is one of the most important ecological factors, more important than light because of the great differences of heat distribution on the earth's surface. All plants have a certain heat range, from a maximum to minimum temperature. Neither of these is best adapted to the life-work of the plants. They develop best in temperature between called the optimum. This varies for different plants and for different funetions in the same plants. Heat influences ehlorophyll-building, assimilation, respiration, - transpiration, roof-activity, development of leaves and blossoms, growth, and movement. Variations below the minimum or above the maximum are not necessarily fatal to plants, most of which can endure a greater variation below than above. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, Noo Vij on on - Many plants have become slowly adapted to a wider heat range. Most of our cereals are natives of a semi-tropical regions. Corn is becoming adapted to more northerly sections. No part of the earth's surface is entirely destitute of plant life solely because of absence of heat. In polar region plants carry on life and reproduction during sunless periods at a temperature ranging from Le te. OF 22 plants out of 27 carry on the work of aime radediatn at that temperature. Many plants must acquire means for protection against extremes and sudden changes in temperature. The latter are more injurious than low temperatures, and sudden thawing is detrimental to plant organs. Plants on eastern exposure often suffer from night frosts since they are reached ny the eariv rays of the sun, Protection against low temperature. 1. Peculiarities in characteristics of protoplasm. &. Changes in characteristics of cell contents. Many contain substances resembling resin. Ex. Snow Algae. One plant endured, unprotected, a temperature -46°. 3. Amount of Moisture. Much moisture predisposes to little endurance of low temperatures. Young twigs suffer most from cold. In polar regions such twigs freeze stiff at night without injury probavly owing to peculiarities of protoplasm. Dry seeds can endure many years in Artic regions. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, No Yue AiR s Winds have great influence on plant forms, and on their dis- privaddion, This is best shown when the winds blow over great, unbroken stretches of land, or where the force is broken by mountains, hills or forests. The inflvence of the wind can ve seen in regions which have a loose, sandy strueture. Air gives freedom of movement which is so necessary to all plants. Plants cannot have have too much air yet may be injured by some of its constituvents. For example, lichens do not usually grow in cities. Smoke is injurious to pinan, There is danger in having too little air. Unfavorable conditions for plants f¢y¥¢ on high mountains are caused by the rarity of the sir. In swamps and pools there is danger of too little 0. Thers the interchange of gases is restricted and consequently there is not enoven. ¢ 0. Too much wind brings a two-fold danger; first it may tear and break the plant structure, but the greatwr danger lies in causing excessive transpiration. Vegetation has heen killed in a single day by a terrific rain storn. Excessive transpiration going beyond power to absorb moisture on account of cold causes low, woody, branching structures. ux., forests on mountains, tundras, lichens and mosses of northern regions. The proof that this is caused by dryness and not cold is that in dry, hot countries, plants asume the same forms, Wind causes the baking of the soil and conseguent dryness. Leaves and branches are often less developed on the windward GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. TENGE, IN i Yo vgpoccscsen issn EE £90... 9 side, occasionally on that side only, branches ani beaves springing from the root, have a chance to develop. Wind often causes mechanical injury to parts. In Jutland looking ‘means the windward side the east appears like a forest, the windward side like a heath. In beech forests, where light wind can enter the surface, vegetation is different from that of the danser portions. He! aeaues regions snow protects against transpiration. Snow lies thickest in Bollows and quiet places, hence vegetation is different there. Uses of wind. 1. Renewal of ox:veen. 2. Fertilization of seats wat forest trees, some depending entirely on wind. 3.The small amount of moisture is probably the reason why the mosses and lichens can endure such low temperatures. 4,.Woody structures are well adapted to low temperatures. Most small plants of Arctic regions contain many wood fibres. Semi- tropical plants when brought to our region, do not receive heat enough to develop their woody structure. Hence their tips die and trees of this class become onl: shrubs with us. Woods in Siberia endure a minimum temperature -60°. (larch forests.) Hair covering. Hairs are cells filled mostly with air, and containing little moisture. Minor protection. 1. Young plants and leaves have many minor protections. In cold regions many plants are covered with a felt- like or wooly substance. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, N. Y., 10 fe Old withered leave@ cling to plants and protect buds, just as man protects tender plants with straw, etc. Such protection does not exclude intense cold but makes it less sudden in its approach. The danger from heat is not so much the burni ng of the tissue but the danger of excessive transpiration. The danger from cold is not so much the danger from freezing but the impossibility of the roots to supply the moisture lost by transpiration. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, N. Y., {4 ! Lecture 4, July 9. Water. Water is one of the necessary elements for plant life. Plant structure and cell sap both contain much water. Quantitatively not qualitatively there is a third factow in which water is the most important factor, that is in supplying the water lost by transpira- tion. The transpiration current is the principal means of supplying plants with food and water. The old theory was that food material was carried along like leaves on sticks in water. The present theory is that each substance obeys its own law and acts according to the law of osmosis peculiar to itself. This makes each substance active instead of passive. In water plants there is no d*finite current carrying water from part to part. Probably there is no transpiration in water plants. Water is intermediate between soil and air. Soil is most stable, air, the least. Air is most transparent, soil least and water intermediate. For plant structure a certain amount of stability: is necessary. Transparency is essential to leaf work. Water alone is best fitted to support plant lifes. Dangers of water relations. This danger has only been recently explained. 1. Plants can take i water more rapidly than they can give it out. The power which forces water from root to stem is called root pressure. Plants may take up so much water that transpiration GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. cannot kezp up with root pressure, Then the air spaces hecome injected, and plant work cannot he carried out. 2. The second danger is that of freezing. Plants best adapted to cold are those which dry up during the winter, as Algae. The drying up prevents freezing, hence many trees can live in cold regions. Too Little water. This is the greatest danger in plant life. 1. Water is not a more important factor ecologicall; than food or light, but:a more variable one since many plants are exposed to conditions varying from moisture to drought. 2. It is not the absolute amount of water which determines whether a plant may live in a certain habitat or not. If a pond contained water for eleven months and dried up during one month, its vegetation would be determined by the one month of drought. Xerophytes are plants that have adapted themselves to dry conditions. Xeropnytes may grow in the water, yet have all the Warming characteristics of desert plants. According to,Xerophytes are plants adapted to dry conditions only. Schimper regards them as plants protected against excessive transpiration. Groups of climatic Xerophytes. 1. Plants of the desert are Xerophytes in their highest and best state. 2. Mountain plants. 3. Arctic plants. 4, Plants of beach and sand dune. QEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. 13 There are dangers of transpiration due to otner in fluences besides climate, Plants may he adapted to dry conditions during part of the year and wet conditions during the remainder. Such plants, according to Schimper, are called tropophytes. Hydrophytes are plants which grow in wet soil. Mesophytes are plants which are adapted to intermediate conditions of moisture. Schimper's tropophytes do not correspond to Warming's mesophytes. Water currents are like air currents in many ways. They favor fertilization and distribution of seeds. Water currents bring about a renewal of air food. Q is not replaced in stagnant water and the water becomes charged with the acids of decay. Vegetation over stagnant water will show diffsrent characteristics from that over running water. Water moving rapidly may cause mechanical injury to the plant structure, but too strong a current is not as dangerous as stagnant water. mrfects of falling water. 1. Falling water is the best cleanser of vegetation. 2. Rainfall supplies water in upper soil layers. 3. Dew is a very important ecological factor. 4. Influence of snow according to Warming and Schimper since it prevents excessive evaporation. Soil Soil in its relation to plants is composed not only of soil particles but also of large amounts of water and air. Soil is the GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, DoF ecncteciscererszaee Bite EGO es: 14 source of many of the foods, for example the nitrates and salts, and is also the source of organic humis, Soil is the best medium to keep plants stable and is also the best protection for plant life and best for vegetative reproduction. The danger of too Little food supply is not so great as that of too little water. Animals. The relation between two life forms acting together is callei Symbiosis, and is sometimes defined as a relation which is mutually beneficial. Now the term includes all relations between plants and animals. Insect and bird pollination are classed 4s symbiosis. The relation of the pitcher-plant to animals is another example ; dead animals oGueiae food for plants ; destructive work of animals influence of plants on plants ; relations of parasitism as shown in the dodder. The rélation of muitualism is beneficial symbissis, as oak and ivy ; Algae and fungus and lichens ; nitrogen tubercle on clovers ; epiphytesyand lianas. A broader example is where a shade plant is absolutely dependent upon the shade of another plant. A still broader symbiosis is a plant society in which the individual members react upon one another. Another kind is the growth of one kind of trees in soil where trees of other genera grew formerly ; as:-oaks succeeded by beech forests or vice versa. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Waa I as caeapsbeed Lecture 5, July 16, 1900. eaves. Functions of leaves. 1. What is a leaf ? Something borne on a sten. Meaning of form, size,arrangement, and direction of leaves. 1. Admission of light is one function. Leaf so placed that thea admission of light is easy. (Photosynthesis) Hence direction is involved in this particular. Perpendicular to the incident rays gives most light. Shape of leaf also involved. Best condition for obtaining light would be for each chiorophyll cell in favOrable relation to the light rays. 2. Admission of C Oq. Same truths hold good with regard to admission to cO>, but CO,is admitted on all sides. 3, Admission of 0. Probably connected with that of COy. This is a universe factor, common to all plants. 4. Emission of 0. 5. Emission of CO,. 6. Emission of H,0. (Transpiration.) Very important. Favorable light conditions would be favorabie also for transpiration. Large blades’ favor it. Transpiration in most plants comes from under side as a means of protection. Transpiration not a universal process except in aerial parts of plants and probably in subterranean parts if soil is dry. 7,. Ruission of liquid water from so-called water structure. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. ee a a eee . Geeet ye. - (Guttation). Drops found in morning vpon corn and grass blades. 8. Supply of food material, If small leaf does not reach its full development, 9. Nature of conduction. Much the same as food supply but especially applies to water supply. Is conduction even ? 10. Protection, This is negative. a. From exposure to sunlight. b. Protection from excessive transpiration. c. Protection from mechanical injury. A banana leaf exposed to wind would be torn to pieces. d. Protection from animals. ll. Storage. a. Water storage in sand and spit plants. bh. Air storage in submerged plants. e. Storage of starch foods less important. 12. Absorption of water as in plants of desert regions or in mosses. Also hairs, as in chickweed. Also absorption of inorganic food materials. 13. Absorption of organic foods, as in the carnivorous plants. 14. Irrigation. Leaves which catch drippings from other leaves. Spiral arrangement and certain petioles sesm to favor this idea. 15. Secretion. 1G. Reproduction, only important in lower forms as in ferns. 17. Protection of other organs, as by the scale leaves, 18, Mechanical necessity, or leaf direction, as gravity in lower leaves, pointing downward. 2 GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Dee, IE cea enncrest cee oe GO. 17 19. Heredity. The grass and sedge form, (ebongation, verticality, narrowness) typical of a marsh plant. Algae. Red Algae f&row lowermost, green next, and brown nearest shore. Water lily shows red on lower surface, Question of color. Fueus a xerophytic plant, resembling salt marsh plants. Meaning of leaf form. surface, expanse, and shape. Best examples of expanded leaf in floating leaves, (water lily), shade plants (Impatiens), and submerged marine plants. Many also srow in sunlight, as rosette plants, and many trees, sycamore, linden, and catalpa. Reduced expansion, compound and grass forms. Ecologically locust is a small-leaved forn. Submerged forms, examples as deeper Algae, grasses, desert plants, willows, pines, locust or divided leaves, shade plants as mosses. Arctic plants. Ferns. The expanded leaf is more favorable to the individual, the compound to the plant as a whole. The divided leaf is the best where there is great need for economy. In the shade leaves tend to grow larger. In the linden, leaves in the shade are larger and thimner than those in the sun but both sweem. to have about the same amount of chlorophyll. Those at the top have need of less transpiration, hence another GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Voy ccc Bae geen LOO), 18 reason for the reduced surface. It is almost universal that the shade form of a plant is larger than the sun form, as poison ivy. Kerner's theory does not aeeane for LHiss« As you go up the plant the need is for protection, as you go down, for light. - Why is the grass form so successful ? The verticality allows a greater number of leaves, horizontal position is best for the individual. Verticality and reduction represent the best type of adaptation to light. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, N. Y., T90...... 19 Lecture 6, July 17, 1900. Kerner's Light Theory. Light. Light an aerial factor in the development of leaves. No green leaves found except in air or water. Scales found in soil. Green leaves called commonly foliage. Red leaves also, since green is masked by red. A third type is the floral leaf. Stems are also often green and do same work as leaves. Sometimes leaves are absent and stems act as leaves. Most stems of herbacious plants are green. Chlorophyll depends upon light. form of leaves. Greater surface in proportion to volume, the greater the possibility of Protosynthesis. A spherical form has smallest surface. All gradations between greatiuess of bulk and smallness of volume and the opposite. A large thin leaf the best type. A stem must have a large volume to its surface, since it mest support the leaves. The less mechanical work a leaf has to do, the fewer organs it must develop. 1. Leaves are phastic. Variations in size and shape under different conditions. Power of adaptation to environment. 2. Leaf direction. Perpendicularity to rays of greater intensity. Position of leaf on tree and movement of the sun. Also variation of the position of sun during different seasons. Absolute horizon- tally best for leaves at Equatow--varies as we come further north. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Vy cece ces £90... 20 Verticality. If a leaf faces horth and south, the souti side would receive Light. all through the dsy. Tie east and south facing as in the compass plant. This receives light morning and evening but not at noon. A perfect compass plant--Sylviun. This shows an ideal condition for prairie plants. A Single leaf receives the most light when it is perpendicular to rays of greatest intensity. Since stems are usually vertical, this is another advantage of leaves over stems with regard to protosynthesis. Direction of leaf also plastic. Heliotropism--tendency of a plant to face or turn wway from tlhe sun. Stems turn directly toward the light. Although diffused light seems hest, trees grow toward the intense light. This is not true in sand spit or desert plants where leaves are positively heliotropic. Structure of leaf. Palisade cells, on upper with most chlorophyll. Spongy tissue, on lower with less chlorophyll. In weak light, upper side most effective, in strong light lower. Chior. bodies change their position with respect to sun. Lab. ex. with prickly lettuce. Cottonwood since leaves move, has same structure on botn sides of leaf. Effect of light on color. Light or dark green probably dependent on physical properties. Shade leaves have darker color, but are so thin that the chlor. shows better. The sun leaves have more chlor. but it is masked 7 ue” Be ve GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tata, Be Vigcisiinane von te in EGO al al In general densit: of arrangemeit is dependent on ata and shape of leaves. The larger the leaves the fewer number, the smaller the leaves the greater number. Kerner says number and size of leaves are related to phylhbotaxy, but Dr. Cowles considers this not absolutely true. That the arrangement of leaves on the tree is dependent upon widely different causes. The mint family. In Maple this difficulty may be -otten over by the length of petiole and its twisting. The question of number of rows is comparatively unimportant with regard to that of light. When plants nave many vertical Vdédv¥dd rows of large leaves, the petiole may get shorter, the leaves smaller toward the top, and wide space petween leaves. In most plants there is a tendency toward the "“nosaic arrange. ea- ment". This reaches its highest development when shape of leaves are modified to fit into each otner. Hackberry, begonia, etc. Another case of mosaic arrangement is fitting angular leaves into each other, as lvy. Still another fittVing smaller into larger leaves. Reading in Atkinson, Chapters X.and XI., pages 13-58. Field lesson, July 16, 1900. Petioles. As a rule monocotyl¢s and gymnosperms have no petioles. siecean and ferns have. =xceptions goldenrods and asters. General shape of the petiole flattened, or crooved ; rounded only in a few, such as the cucumber and squash. Petioies are more apt to he colored than leaf blades. In cottonwood the petiole is flattened _ vertically giving the opportunity for free movement. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Vy cocci 22 Desmodium shows pulvinus of thickenings at base of petioles. This is a common feature of all Liquimnosae. Stipules. Two classes. 1. Green persistent, usually larger. 2. Non-green, deciduous, usually smaller.. ‘Wanting in magiy plants. Leaves growing under poor conditions take the form of leaves on the upper side of the normal plant, provided the ‘show variations in shape of leaves. Ex. Peppergrass. Plants. Collinsonia Canadensis. Horse-Balm. Desmodium nudiflorum. Tiek-trefoil. Sanicula Marylandica. Black Snakeroot. Actaea alba. White Baneberry. Asclepias incarnata. Swamp Milkweed. Circaea Lutetiana. Enchanter's Nightshade. the plants GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. + Ithaca, N. Y. LGD... 25 becture 7; Jute 16, 1900, iene (continued). Water plants with regard to influence of light. 2 great types of leaves. 1. Floating as water-lily. 2. Submerged. Leaves of water plants are in position to receive sufficient light. Many water plants have two kinds of leaves, floating. and submerged. Ex. show that such plants can change the $¥Axv¥ kind of leaf under different conditions, Proserpinzaca very plastic, shows first dissected, then entire, ‘then dissected, then entire under different conditions. In water plants other influences besides light seem to affect the leaves. Finely-dissected leaves the type the general tvpe of submerged leaves, since that form allows the light to sift throtgh to a great depth. Rosette plants. Not so common here, Dandelion, Sedum. This form cannot be explained by light relation ; vet, though plant as a whole avoids light, each leaf is so placed that it may receive some light. Tree rosette as tree fern, yuceas, palms, etc. Here leaves ‘ seem to come under the same conditions as in the true rosette. C ound leaves. Compound and finely-divided leaves Kerner considers an GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, No Voy cece no . £90... 24 adaptaSion for more light. Other things also affect nek (gigas Theoretically leaves should be more compound above but the reverse is usually true. Plants may be cone-shaped as mullein with broad leaves, and the inverted cone with dissected leaves as Ambrosia. This is Kerner's view but it is not adjustable to facts, The shape of a leaf . PUAAY does not determine the shape of * plant, but the surroundings generally decide tt. The elm becomes cone-shaped when grown in the forest, but in the open is the reverse, Kernor's theory of light does not explain Leaves wholl:. As to form the leaf is somewhat influenced by light but more so by other factors. As to size, horizontally and vertically, light has very little te do with it. As to position and srrangement, Kerner's view is much more important. Admission of CO.. What is influence of CO. on leaf shape and arrangement ? CO, is necessary in large quantities. Conditions favorable to admission of light are alos favorable to admission of COs ; but light only enters from one side while COg comes in from all sides, Warming thinks that since CO, is so plentiful there is no necessity for special modifications to admit it. From recent experiments it has been proved that CO, is more plentiful in lower leaves hence CO, may influence the shape. Admission of O. No question as to quantity except in water-plants especially in GEO, F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Vo, cece oe Cl 9O.., oF stagnant water. Here small quantities of 0 is presant and animals obtain most. From study of water plants it has been shown tnat large spaces for air always exist. Need for O therefore modifies water-leaf. BmMission of CO. and O. Unlikely that these factors influence shapes and forms at all. Transpiration, One of the greatest factors, createst in size and one of the greatest in form. Transpiration mainly determines difference between sixe of leaves in shade and sun. Extremes. Impations. Large thin entire leaf and Saticormia where leaves have ween lost entirely. Linden shows this, since leaves ure larger near base, and thinner, smaller and tiicker above. This ean best be explained by transpiration conditions. Need for protection from excessive transpiration changes plants from howingntaliey to verticality as seen in the desert t:pes. Succulent plants explained best br this factor. Rosette plants can also be explained as to those in cold regions, but desert plants iot so easy. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tihata, No Losgencicckiicnosens ‘ Le vel GO.. 26 Leeture 8, July 19, 1900. Transpiration (continued). Peat bog plants. Plants with a pronounced Xerophtic structure. Shimper says the hature of the peat_bog leaf is caused by difficulty of plant to obt*sin proper nourishment, as water free from acids. Hence even for. a plant growing in the water, this hind of water is essential. Stahl of Jena, one of the greatest ecologists of the day. Paper on Sleep Movements, dealing with compound leaves. O1d meaning of motile leaf was supposed to be the protection against cold. (Darwin.). Stahl shows that warmer climate, greater movement. His view is that closing at night is to further transpiration. An expanded leaf would collect dew, while 4 vertical leaf would shed it. Another point would be the position of the stomata. The Legume family is better adavted to its environnent than other families because it can work at das by protos:nthesis, while at night it can collect materials for food. Other plants must do both st once. The Legume family is best adapted by its stomata and motility hs FeR GH transpiration in early morning and Jjate afternoon Stahl also thinks that the petiole of the poplar is an adaptation along this line. The reason that a plant seems to try for a greater transpiration is that the Breater the current, the greater gmount of salts carried. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, IN: V gy cvcdisccessscses si) LGB ay This was old sGAaIesicdt Siew. Now it is Ceewant that each’ ~ substance is carried into the plant independently. Stiil Stahi's idea is true so far as plants are able to use up the salts carried py the water. Meaning of leaf teeth, Veins go up into the point of the tooth. Hydrothode. A raised surface gives greater opporttinity for evaporation. Henes the importance of the pyramid-shaped tooth of the leaf. The tooth is a safety-valve to permit passage of water ------ : 7. Gutation. The hydrothode or water pore is the usual form in most plants. Xerophytic or sun forms have no hyfrothnodes ususlly, but they are common in shade plants. Root pressure goes on, but transpiration often ceases at nignt. Transpiration is giving off gaseous water through air spaces. Gutation is giving off liquid water through veins. Hence gutation seems most important factor in deciding margin of leaf. 8. Supply of food material, Very important factor. WAchter published paper on leaves of water plants. He found that arrowhead leaved varied considerably in going from margin out into the lake, from full normal leaf to a ‘petiole. It might be explained by difference in light or difference in currmt, but Wachter found it dependent entirely upon richness or poverty of the food. supply. Alao cases where largest leaves are lowest. It may be because GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Vij cece ves wi sie degen 26 these leaves receive best supply of food. If COg is more abuzdant near the ground then lower leaves would receive most. 9. Nature of conduct ion, Embryonic leaf largely veins, only matured leaves filled up. Conductive tissues must be developed before chlor. tissues. Eight and nine determine size of leaf or upon amount of food material. 10. Protection from exposure. Light, heat and drought. Only another way of expressing transpira- tion. ll. Protection from mechanical injury. Either due to wind or water currents. Direction of a leaf, plastic ordinarily, is greatly modified by wind or water. Ex, common weed and pond weed, also Algae. Kerner suggest s this plasticity also explains compounf leaves, as in banana leaf which has been torn by the wind. 12. Protection from animals. Old view not so much accepted now. Did thistle develo» spines as protectkon against animals or did the spinous originally serve as a protection ? 13. Storages--of air and water. Large leaves and petioles often come from having large storage cells. Storage of food materials also modifie@ leaves sometimes, as those of a lily or onion bulb. 14, Absorption of Had. Ex. leaves of mosses and water plants ; also seen in hairs developed GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Vy vec Lo LG0.... 29 on desert plants. Cup plant in west, with verfohate leaves in which water collects and is absorbed by special glands. 15. Absorption of organized food materials. Utricularia, Droscera, Sarracenia. 16. Irrigation. It is necessary for leaves to get rid of water which falls upon them. Kerner sdys there is a relation hetween dripping-points of leaves and the water-supply to the roots. Spiral arrangement of some plants also favors irrigation, hence it seems to partially explain phyllotaxy. 17. Secretion. Glands can scarcely be said to modify shape of leaves. is. Reproduction Does not usually modify leaves except in case of ferns. 19, Protection of other organs. Scale leaves protecting buds. In Viburnum scale leaves in winter become green in spring and develop chlor. 20. Flotation. Air spaces may also be developed for purposes of buoyancy. 21. Mechanical necessity. | A last resort except 22. Heredity. Something due to past environuwent. Ex. Asparagus, Alao may explain the phyllotaxy of leaves. Venation as well. Those things which are least variable are most apt to he due to heredity. Variation GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca,, No Vi, secs See 90... 30 seems to come from difference in environnents. But unvaried forms mast have been caused once by definite conditions. Forms which are variable do hecome fixed in time and when plasticity is once lost, it is lost forever. Reading--Coulter--Dhap. IV.--Shoots. p. 53-88. Field Work July 18, 1900. To study development of leaf teeth, use Viburnum, Red Osk, Chestnut, Circaea, Sycamore. 2xamples of climbing plants. Poivgamum scandens, Bindweed. Ampelopsis quinguefolia, Woodbine. Cuscuta, Dodder. Smilax. Apios, tuberosa, Hog peanut. Rhus toncoden, Poison ivy. Amphicarpaea monoica, Hog-peanut. Climb by tendrils, stems, petioles, suckers, adventitious roots, , holdfasts. Lee Cut-grass, 2 halfsclimber, backward hooks on the leaves. Autumn coloration may be defined as the color of a dying leaf. In such eases the color is usually; stronger in the upper side of the leaf, seemingly associated with light. Disease will also cxvse coloratiou in plants, as rust in the dandelion. Field Work July 19, 1900, Roots and other absorbing organs. Roots are generally fibrous. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. ithaca, No MV vyscse ccc 6 oe . 1G0... 31 1. Because by this form greater varieties of soil can be reached. 2. Because such forms pass more easily around obstacles. The mechanical functions are as holdfasts and for purposes of absorption. The reason for general downward direction is undoubted- ly force of gravity. This geotropism may be the result of heredity. Originally the roots may have assumed this position in its search for food and the habit may Bave hecome fixed. Exceptions are common. as aerial roots in ivy ; water hyacinth, etc. Cypress knees, supposed to be the result of growing in stagnant water for purposes of aeration. Here another force works against seotropism. od study of Leucobrvin. Celis connected by pores. Three layers, with chlor. in the central one. Air cells on surface guarding chior. cells within. If placed in water, epidermis becomes transparent and leaves avpear green. Can be grown for several vrears without developing rhizoids. Leaves absorb water as in Sphagnum. Prof. Barnes of Chicago University believes that mosses absorb — water entirely through leaves, not at all through stems. Dr. | Cowles believes conduction through leaves more important than through stem but not entirely the way. Mosses if placed in water hecome wet immediately, showing the absorption. Lichens absorb water eagerly. Probabl: take in also sore mineral food from the substratum Since they decay rocks. Asclepias incarnata growing in the water showed roots containing chlor. . GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Voy crsecciceinnin This is not uncommon with plants with aerial rootlets or in water- ‘plants. It might be possible under special conditions to modify the structure of roots in this respect. If roots of water-plants contain chlor. it might be of advantage to the plant, since all the work can go on near the same spot. This would save a tremendovs amount of expenditure of energy. Monotropa uniflora. Probably a degenerate form, since it bears scales and is one of the Fricaceae. It is not a saprophyte, since it lives hy means of a fungus at its roots, mycorhiza or root-fungus, a plant which gets its food partly by other plants, partly from soil, is called a pymbiotic parasite. Duckweeds. Spirodela, Many roots. Temna, One root. Woaffia, No roots. Botanists regard duckweed as a reduced type of calla. Bladderwort is also a reduced type having lost its roots. Beech trees have no root~-hairs. Live as do many other trees, partly by bhe root- PUTS Ls Same fungi cause nodules on Lequiminosae. Cladoma, Reindeer lichens. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Vy crrccvccrecccstiiie oe EGO. 33 Field York Jtly 20, 1900, “Life History of a Growing Beach Veretation, Beach vegetation is usually Xerophrtic. The beach may be divided into zones, lower beach, middle, upper, and mature or fossil beach. The lower beach was characterized by the entire absence of plant life. Plants af¥e unable to adapt themselves to such variations as growth on this xone would aise aaa Plants may grow in water or wpon land since they need a certain stability. The beach shows a certain grxdation in the plant life though no strict line of demareation can be drawn between the different zones. Next to the zone of the lower beach is tnat of anival plants. During certain seasons of the year the water rises more than at others. Therefore plants which obtain a foothold there, must be able to complete their life work within a short time. The zone of annuals along L.I. Sound corresponds to the same zone along Lake Michigan. hvery species found in Chicago except the bug-seed, is duplicated here. Plants in Zone of Annuals. 1. Cakile Americana, Sea-rocket. 2. Xanthiun, Gaeitepued: 3, chenipodium album, Lamb's Quarters. 4, Polygonium convolvulus, Bindweed. Qenothera, Evening Primrose. 6. Salsola kali, Saltwort. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, No Yoyo oo 2 £90... ae ee 7. Solidago sempervirens, Goldenrod. 8. Atriplex hastata, Orache. 9. Huphorbia polyvgonifolba, Spurge. 10. Lathyrus maritinus, Sand Pea. 11. Strophostyles Angulosa. Cakile, Salsola, Euphorbis and Xanthium were the dominant forms on this beach. The plants of this beach are the most xerophyte. Though near the water they are too far removed to be reached by it, and are expoded to stronger winds which tend to dry the soil which containing little decaying vegetation cannot hold much moisture. These plants receive littie shade from other iene, Saiisola has reduced, succulent leaves and thin epidermis. Many plants of this region have no hairs. Xanthium was the only exception to this rule found there. Cakile has succulent stems and leaves but the leaves are not mieh reduced, yet this plant is always found in exposed conditions, being one of the first plants found on a beach. Euphorbia is characterized by folding leaves, a milky juice and spreading habit. The upper beach is always free from wave action.. It is usually a young region where perennials hegin to replace ajnvals. It may be called the Zone of Perennials. Plants of Zone of Perennials. 1. Xanthium, Cockle-bur. 2. Amorphila, Sand read. 3. Lathyrus maritinus, Sand pea. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Yijo-- eee A “te Salsola kali, Salitwort. and 7, 3, 1, 5, 9, of the list of annual plants ; besides 10. deg LAs 15s 10. Rhus toxicodendron, Poison ivy. Helianthus, Sunflower. Arenaria peploides Atriplex hastata, orache. The third plant zone is exposed to less xerophytic Plants of third zone. Amopnila, Sand reed. Prunus maritima, Beach vin. Asclepias cornuta, Milkweed. Rumex acetocella, Sheep sorrel. Lenaria vulgaris, Butter-and-hegs. Verbaseum thapsus, Iullen. Myriea cerifera, Bay berry. Artemesia candata, Wormwood. Chryvsopsis falcata, Golden aster. Artemesus stelleriana, Dusty lliller. besides 10, 7, 5, of first list and 10 of, the second. conditions. Lathyrus shows sleep movements, its leaves assuming lateral position during the day, thus preventing transpiration. Ammophils has a strongly xerophytic leaf having the power of folding. it has also a long, linear, migrating stem. Beaches are of two kinds, xerophytic and hydropliytic. in the former there is a zone without plants, in the latter, plants extend to the wdter's edge. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, N. EGO. Many attempts have besn mad? to explain why the zone of annuals is so similar along 411 beaches. One extreme theory is that the striking similarity of ocean and lake beaches was caused by the former salt condition of Lake Michigan. Plants grew inder salt conditions and remained after these conditions disappeared. Warming’s view is th:.t a halophyte is esseutially a xeropfhyte. Salicornia herbacea is the only one which will not grow away from salt water. 4 Geographical distribution of coast forms. 1. Those that grow anywhere. cheniopodium album, Lambs' quarters. Oenothera, Evening Primrose, Asparagus, Juniperus Virginiana, Red Cedar. 2. World-wide coast ferns. Cakile. Saisola. lULathyrus. Ammorphila. The first grows along the Atlantic Ocean, the others, in the northern hemisphere. Typical Dune Plants. Artemesia stellariana----Eastern Asia, Massachusetts, and Long Island. Great Lakes and Atlantic. Cakile. Salsola. Ammophila. Xanthium. Euphorbia. Atriplex. Artemesia candata. Hudsonia tomentosa. Ihrrica cerifera. Not found on the Lakes. Sq hideca isceRaeetnemk, Fs ¥%o tavkeeod. Prunus maritimus, N.B. to Va. Artemesia stellariana, L.1I. to liass. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, N. Y.,..~. 37 Lecture IX, Summary. (With regard’ to what has developed leaves.). internal anatom:. Highest type of chloroplasts formed in highest plants. Nature seems to have heen experimenting in the Algae. Leaf-formn. Lowest form--unicellular, first--Protoccoccus. Then filamentose, then expanded type. Natural order of evolution. A plant to become multicellular must become filamentous, expanded, or show evolution of an internal atmosphere. Adaptation of form to external environment in lower forms; in higher also accommodation ek be made to the internal atmosphere as wellas outward surroundings. Direction of growth. Lowest vlant more or less horizontal ; in higher liverworts we have the approach to verticality in stem. Evidence from Paleontology, especially may be worked@/d out witht he conifers. A perfect series can be made out between cordatss leaf and the needle upon one side and the ginkgo on the other. A leaf is a mean between extremes ; the result of forces acting in opposite ways, light and food supply against need for protection. Ulva an ideal of what a leaf should be if develoved from a condition of light alone. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, DN! Mogg i Greripcescverleosas za a Leaf form including shape and cross section due mainly to light and need for protection but aiso ‘ a necessity for plasticity as in compound leaves, the best examvles of which are found in the water. Size in contrast to form seems to be largely a matter of food supply. Sometimes form may also ve modified by food-supplyr. In determining direction and arrvangement the light relations come in. Certain rays are absorbed and certain colors reflected. Green commonest color in plant as to leaves ; due to chlor. which works only in sunlight, though plastids are present. Decolorization of green leaves due to blanching in the darkness ; to disease ; Exper. show iron is necessary to presence of chlor. Chlorosis a and Etiolation or bleaching, both diseases. Partial covering of plants as by sand dunes produces decoloration ahove. In bullrush zones of color were shown. In spring, leaf grows so rapidly that development of chlor. is not apt to keep up with the growth of the leaf, hence the brilliant color of fresh spring foliage. White and yellow colors come from disease ; the color being due to the degeneracy of the plants. White and vellow are purely pathiological conditions. One theory is that the green color has no ecological meaning, the other that it has. It may have been evolved by the evolution of nature. More rays absorbed at the ends of spectrum than in the middle. At the red end there is the greatest amount of proto- GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Yojeeccccc GO. synthesis taking place, especially at the vellow band. Heat is also most developed at this end while light is best developed at the violet end. Hence green is an intermediate color it may be the color of chlor. since it absorbs the other rays such as the red and blue. Cyanophyceae--blue-green Algae--live best in warm atmospheres. Significance of Reds. Sometimes green does not develop a great enough amount of heat, so red leaves may be developed in the spring. Stahl and King have experimented on red leaves of maple and beéch. Greater heat - given off by red leaves. Henes it has been thought that the red of leaves is developed. ‘Often on the lower side of shade leaves and water leaves for the conservation of heat. Many plants which live over winter as mints have red color on lower surface. Autumn Coloration. Caused by- introduction of new substance. Anthoeyan, if acid it is » if not acid . This substance is a result of preaking up of the chlorophyll. Kerner considers the leaf continues to do its work, a short time after the red color is found. Objections to Kerner's theory. 1. It appears to contradict itself. 2. Amount of temperature change, very small. Observational Objects. 1. Spring leaves generally red. 2. Leaves may turn red whenever their work is done. QEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, N. Y., 40 5. Another objection is that tropical plants show the most cola: Overton published an article upon coloration in plants. His theory is that the amount of sugar in a plant depends on the amount of red color. Spring and fall, times of the conduction of sugar. A third view is that color, especially green color, has no ecological meaning. Read--Coulter--Chapter V.--Roots, also Discussion of Xerophytes--p. 1935. Warming--p. 177--on. Laboratory OQutline. Absorption. Root-hairs, typical structure in any plant. Rhixoia@s in mosses and liverworts. Leucohryium and Sphagnum. Hair on Chickweed or Stellaria. Parasitic absorption in Cuscuta. Mycorhiza of Alder. _ Legume tubercle. Monotropa uniflora. Aselepias roots. Lichen. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Wha, WF, Lecture 10, JUly 23, 1900. Stems. One of the most important features is the direction. Another, epe 5 Still another, branching. Color of stems an additional factor. Evolution of stems. In the lowest Algae we find no stems. Even higher forms as Ulva have no true stems, but in Fucus we have a true stem, since in ee center the cells are closer together giving stiffness. In Algae of the Pacific coast large stems are often found. Fungi develop no leaves, but perfect stems as do also liverworts. Mosses show a real stem with definite roots below and definite leaves above. Going up from the mosses, the stemless form is the exception. The erect stem is found ina great majority of plants, and was first developed in the mosses. Kerner calis tie stem an indirect adaptation to light, but other factors also influence it. in Sunes the light relation is insignificant. Another theory is that carrying a plant above the ground favors reproduction, spores or pollen being carried by insects or wind. Kerner's theory with regard to stem is that elongation of internodes faymsps the development of leaves. Ina forest trees are apt to crowd upward towards the light. Palms do not branch but bear all leaves on the erect stem. The greater the branching the greater the chance for leaf display. The petiole further relates the leaf to the light.,, Tree ferns and Monocotyledons have no GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. .. Ithaca, N. Y., 42 petioles or bpanches. While in Dicotyledons there is great ability for branching and leaf display, the stem gives nothing to — plant but mechanical support. In some plants it may he better not to have so great a chance for leaf display since it requires so strong a mechanical support. This necessitates a large supply of food. The stems of fungi may be connected with reproduction, and sporophytes in mosses, with the same thing. I:: most of the rosette type, the chief use of the stem is probably for purposes of reproduction and it may also have influenced the long stem of the \ millein, The same principle is true though perhaps in a less degree -in trees, Since many trees are anemophilous. The cylindrical stem is most common, then the square, and lastiy the triangular. Sometimes we find the flat stem. The cylindrical is probably the strongest. Round and square stems can best bear the weight of their branches. Shape of stem may be influenced by wind which if prevailing may elongate the diameter of me stem in direction of the wind changing a cylindrical stem to an elliptical one. Tree stems need mechanical support and trees usualiy have rounded stems. Where there is little need for protection a square stem may answer better than a round one simce it requires less strengthening tissue. Square and triangular stems have more surface in proportion to volume, hence can do more chlorophyll work. Coccoloba, an extreme xerophyte, is the best example of a flattened stem. It has lost its leaves and the flat stem does the leaf work. Round stems have less surface, hence less transpiration. Color of Stems. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, N. Y., 45 Most herbaceous stems are green. Red is found moreoften in stems and petioles than in leaves. Kerner explains the red stem as the red leaf ; that the red is a protection for the withdrawal of protoplasm. The bark of older trees, usually dark probably because cells are dead. Exception, the birch. There colors are probs«bly due to presence of waste products. Field Work Jule 24, 1900, is trees 2ast slope. Quercus prims Chestnut Oak. Quercus coccinea Quercus rubra Red Oak. Quercus alba Acer rubrum Red Maple. Castinea satina Americana Chestnut. Fagus ferringinea Beech. Carya alba Sheli bark Hickory. Betula lenta Sweet Birch. Prunus serotina Wild black cherry. ’ Prunus cerasus Cultivated cherry. Robinia pseudocassia TLocust. Nyssa multiflora Sour-gum. List of Shrubs. Cornus Florida Dogwood. Clethra alnifolia Pepperbush. ‘Gaylussachia resinosa Huckleberry. Vaccineum stamineun Blueberry. Vaccineum corymbroseun Swamp Blueberry. Scarlet Oak. White Oak. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthattt, No Vo soscccrasapige 6 oo were T90...... Vaccineum Pennsyivanicun Amelanchior Canadensis Rhus toxicodendron Viburnum dentaturi Vibernum acerifolium-~ Hamamelis Virginica Lindera benzom Kalmia latifolia Ampelopsis quinquefolia Vitis aestivalis Myrica cerifera Laurel is usually found on treeless slopes. “ Vaple-lea Dwarf Blueberry. Service-berry. Poison Ivy. ved. Viburn um Witch Hazel. Spice bush. Locust. Virginia Creeper. Summer Grape. Bay berry. If found ae in forests, it probably dates back to a time when the land was treeless. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY- Ithaca, No Yor neevo 190... 45 Field Work. July 25, 1900. Cooper's Bluff. The bluff was a steep, sandy slope extending down to a flat beach. It was a Kame, part of the terminal moraine which the glacier left upon its withdrawal from Long Island. The situation was different from that at Lloyd's Neck. Here the shore was heing gradually washed away, there it was being built up, hence the vegetation showed con@iderable differences. At Cooper's Bluff older formsof vegetation were found close to the shore. As the waves washed out the beach, the cliff became undercut and land-slides frequently occurred, bringing the higher forms nearer to the shore, while at Lloyd's Neck, the vegetation apveared to be going backward. There seemed to be four zones. 1. The Beach Zone, from the beginning of vegetation to the slope. Hefe we found Strophostyles angulosa Atriplex hastatum Orache. Salsola Kali Saltwort. Chenopodium album Lamb's Quarters. Polygonatum convolvulus Black Bindweed. Ammophila arundinacea Sea Sand Reed. This locality was poorer in its flora than Lloyd 'a& Neck. There were as many species but fewer plants because of the encroachments of the sandslides and waves. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Yoyo eer 2 Mewes 190.0... 46 In one place was an old tree trunk filled with soil and here under more sheltered conditions we found Euphorbia, a Rumex, Bidens, Sea-rocket, and others. II. Cliff Zone. Here were reall: three regions, showing some differences in the flora ; the bluff proper where were found me ; Trifolium &rvenses|-> oA = a he Linaria Canadensis’ Achilled Millefolium Rumex acetosella Oenothera Erechtites hieracifolia Rhus Toxicodendron Erigeron Canadensis Chenopodium album Polygonum Convélvulus ~Blue toadflax. ~Rabbitsfoot clover. Common Yarrow. Sheep Sorrel. Primrose. Fireweed. Poison Ivy. Horse-weed. Butter-weed. Lamb's Quarters. Bindweed. 2. The landslide flora where many plants frowing naturally at the summit had been brought down Alnus Betula lenta Salix Amelanchior Rhus toxicodendron Poa compressa Mvriea. eerifera. on the slope. Among these were : Alder. Birch, Willow. Service-verry. Poison Tvays Grass. Bayberry. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, N. Y., elie ae aN ess gt 190." - Rubrus occidentalis Agiostis Lactuca Achillea millefolium Ampelopsis quinquefolia Solidago. Vaccinium Pa, Viburnum dentatum Prunus Hypericum perfoliatum Black Raspberry. Bent-grass. Lettuce. Yarrow. Virginia Creeper. Cherry. St. Johnswort. Taraxacum officinale Dandelion. Cornus florida Dogwood. AT 3. The oasis flora where the presence of little springs produces @ growth of mosses and liverworts. III. The Margin Zone. Here were found most of the land-siide forms. IV. The forest region beyond the margin. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY- Ithaca, N. Y., Leeture li, wuliy 26, 1900, 1. Erect. Stems. 2. Lianas. rs ey Tne philosophy of stems. is really the philosophy of ico Loew: The stem largely decides the character of the plant. ‘All climbing plants are called leaves. Great. vanietz: of means of climbing 5 tendrils, roots, thorns, paRiciee, shane, etc. bianas ase aya in rien tropical forests, dio found in our own region growing upon trees. Warming and Kerner regard the liana as a unique and economical method of getting at the light. Large expanse of foliage with little mechanical support. As forms become independent they have eradnae difficulty in living ; hence the eee not so so0d a chance as the tree upon which it grows. Chief danger is death of the host piend, also the liana may be torn away by the wind. Stems show compensation. 3. Epiphytes. : Attempt to meet same conditions as the lianas. Here we have few, except lichens. In Florida there is the long MOSS. Another theory is that it is the result of a struggle for life in a crowded forest. Mere existence is only possible when away from the crowded ground. 4, Creeping stem. Example of two types--clover and raspberry. First creeps along the ground and roots at the nodes. The se¢ond has a walking habit, as has also the camtosoris rbizophyllium. Great meaning of this form of stem is reproduction ; to increase the area of the plant. Vegetative reproduction. Also the migration to a new field where food GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, Ni Voy org: 49 Prostrate stem. Not related to creeping stems since they do not root at the nodes, hence no vegetative propagation or migration. Protection the common theory which seems true in Arctic plants. A second theory is that of insufficient food supply. A third which seems more plausible is that of mechanical necessity. 6. Rhizome. No essential difference between rhizome and creeper except that one is aerial, the other subterranean. ‘o Three tipes of propagation. 1. Linear type, unbranched. A migrating form. Puncus balticus, “example. 2. Radial type, as clover, forming a mat, center hollow. Fairy ring, often found in fungus growth.z Most common type and best one. 3. Circular type. Migration in a circle, found in some orchids. 7. Bulb and tuber type. This represents the deepest form of stems. Protection one great factor ; another, need for storage. This type nota@piously conspicuous in desert plants. A reason for such forms is shortness of growing season and great length of unfavorahbie conditions. Shade conditions also favorable to bulbs. 8. Rosette type, one kind the vermanent rosette; the other, the a winter rosette. First, xerophytic in habit, desert plants. Need for protection, very important factor in rosette form. In the temporary rosette shows exposure to alternating conditions. Ex. Mullein and Oenothera. 9, Multicipital or Stem--Base--Complex. Reduction of stem to a GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, No Voy cece + ei eB. 50 point, Vewain, also dandelion. A series of stems on'one stalk. Ecologically it differs little from rosette stem. Increase of stems but not of plants. 10.Floating types which vary. + 11,Thallus--no trne stem. Stem and leaf are one and are flat, as Marchantia and duckweed. In Algae the stem and leaf have not been differentiated, but the duckweed cannot be so explained. Two theories; one, that water habitat is more favorable for plants hence the plants lose all different parts, the other, that the parts are lost from poverty since the water form is less favorable. Latter view seems to be more sensible from experiments which have pexr made. Uses of stems. 1. Display of foliage and flowers. 2. Vegetative reproduction. Vertical stems favor light relations. Horizontal stems favor reproduction. Oe Protection best favored by the stem working downward. 4, Mechanical support. 5. Conduction. The 4th and 5th incidental to the 1st. 6. Leaf work. . 7, Storage. Conflict between lst, 2d, and 3d causing the different kinds of stem. Moss shows first two types, in the protonema and gametophore. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Dthaca IN Voog weletiscensoumonnien ee ‘£90 Laboratory Work. Protection. Thick stem--Cedar and Laurel. Hairs-~-Mullein, Artemesia. colorss-~Physical conditions. (Degenerations of chloroplasts.). Flowers--Red and yellow leaves. Glands. \ Mint, St. Johnswort. (depressed) Rose calyx (stalk gland). vdathodes. Any leaf teeth. leaf Movement. (stomata). Tubercies. hts iza. Orchid roots, fHabenaria ~\Goodyearia GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, N. Y..,... 190. On wo Lecture 12, July 27, 1900. Roots. ls Absorption. a.Soil plants. More-uniform in structure than stems or leaves. ‘Ordinary roots much branched, ends smaller than those of stems being the root-hairs. Chief function of root-hairs is absorption of water and salts in water ; hence root is not organ of absorption but of “display. Osmosis governs the absorption of different substances, the root-hsirs having the power of selective absorption, hence plants have really an advantage over animals. ‘Two functions of roots are display and conduction. Why is there difference in size between root-hair and leaf ? 1. It is capillary to enable it to penetrate the soil. 2. It can come into more intimate contact with the soil particles, every cell coming in touch. 3. It has grenter amount of surface in 4 given volume, than any other form could have. Liverworts have no true roots, but rhizoids, which are like root- hairs in function put like the root in tropisms. In mosses they are more highly developed but a great gap between rhizgoids of mossés “and roots of ferns. In a few land Algse like Botrydium, we find rhizoids developed. b. Water Plants. If Indian corn is grown in water, root-hairs are lost, but many GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, Ni Vig. ccc coe IQ0..... water plants as eel-grass, contain them. Reason for many root-hairs, the increase of absorbent surface. leaning of reduction--Two theories. 1. Food obtaining so easy that organs disappear. 2. Conditions so hard that the plant is unable to develop all its organs. The food is so scattered through the water that it is difficult aspecially in stagnant water, for the plant to obtain what it needs. Why Bede many water plants so similar ? Because of similarity of environment. Water plants show gradual decrease of root organs and use of leaves as absorbent organs, hence leaves take on a root- like, finely divided form. c. Saprophytisn. Plants which obtain their food from decaying ameaniee matter. Many fungi are saprophytes, but few among the higher plants. Ali ‘plants seem to enjoy some decaying organic matter, hence most plants are saprophytes in part where they have an opportunity. Autophyte-- _& plant absolutely independeiut. a. Parasitism. Plants which live on living parts of otner plants. Intimate r relations of parasite and host. Rafflesia--no leaves, no stem, hut a root system, like fungal threads and immense flowers. Found in W. ‘h Some plants are both saprophyte and parasite. Associated with this feature, we have carnivorous plants. ée. Mutualisnuy---where two organisms are of benefit, each to the other. EX. agers of heguminosse. Ikycorhiza in Beech, Bireh, Alder, and many of Heath familv. These are nitrogen gatherers. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Voy erence een T90..... f. Lichens, A lichen is a plant complex, made up of Algae and Fungi. Three things to be considered. 1. Relation of whole to what it is attached. If on a tree it must be an epiphyte or saprophyte. Both theories held, but neither proved absolutely. 2. Relation of Alga to Fuuygus. 3. Relation of Fungus to Alga. (a) Anatomy~--old view--that Alga and Fungus were derived from same source. This disproved. Experiments have been made by which lichens have beennade, showing the two plants absolutely independent. (bo) Mutuslism--2da view. (ec) Parasitism. ; Fungus must be benefited. As to the Alga, it is an open question. An equal case seems to be able to be made out both for parasitisy and mutualism.,. Jichens are xerophytes, but Algae and Fungi are largely hydrophytes. This seems a proof on the side of mutualism, Soredia--a means of reproduction, composed of a few iwphae of . - tl Funsi and a few Alga cells which is not unlike a gemma--iven off i by the lichens. (di) Helotism Half way between the two--Warming. 2. Holdfast Organs, Roots are decidedly holdfast organs, also rhizoids and root-hairs. Tamaracks have not 4 good opportunity for vertical root development, GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, Noe Voy ccc cc Photo fom aaah 790... hence are easily blown over. Roots also are contractile as in pulbs. Climbing roots. oe 3, Mechanical support. Banyan-- Indian corn--prop roots. 4, Storage. Turnip--Beet. 5. Leaf work. As chlorophyll develops in roots of water plants as in water plants and epiphytes. G. Aeration. Cypress swamps. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, N. Y..,.. : Lecture 13, July 30, 1900. | | R roduct ion. A. Vegetative. ilost primitive and most important kind of reproduction ecologi- cally. Many Algse depend entirely upon this. In liverworts and mosses we find gemmae ; also almost any part of thallus or plant. Protonema of mosses very wonderful since a great clump may grow fron a protonema which is produced by a single spore--in ferns many plants fro 4 single spore. Ii higher plants as Blodea. One individual plant was taken to Europes, either a pistillate or staminate, and now all the rivers of northern Rurope contain it. Water-hyacinth in St. John's Kiver, Florida, Duckweed. B. Svecialized reproductive organs. A sexual spores in Algae, tosses and Liverworts and Ferns, Flower and Sead. A flower is a ree of orBans modified for , Purposes of reproduction. Pistils and stamens, real reproductive organs. To prevent self-fertilization, we have l. Proterandry and proterogyny. 2. Imperfect flowers. 5. Stigma above stamens. 4, Polien impotent on its own pistil. ‘Cléistogamous flowers--violet. It may be the flower has become too Specialized for insect fertilization. In Cruciferae many cases of Self-pollination are found. Willows-~-insect-pollinated, .Poplars---wind-pollinated. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Voy cece £slae oe G Os B7 leaning of floral envelopes, Why is a calyx ? Ls Protection of Wid. 2. Protosynthesis. Useful for manufacturing materials for local needs. 5. Protection of seeds. Potentilla Canadensis, an example of all three. Kooders found in many tropical flowers, hrdgthodes in the calyx. Why is a corolla ? Darwin, Cubbeck, Itiller, and others believed the corolla was for the attraction of insects. Plateau published experiments in whieh he proved that insects were color blind, hence the petals do not attract insects at all. War waged. at orsens tins between the two factions, though Plateau's theory seems to be not very tenable but the question still remains .open. ‘Seeds and Fruits. Nearly every wing of seed is green st first, hence Prof. Lloyd thinks that it oes the work of protosvnthesis. r ction. A. During Growth Period. B, During Rest Period. Cs During Period. For growth hairs which are usually stiff, rigid, and dead. ' Position of hairs often explained conditions. Direction of growth in hairs.. Why are hairs so usually stiff ? A vertical hair is GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY® Ithaca, No Voy cence 5 eke DO: BS best protection against animals, horizontal against transpirstion. Hairs generally found o: shade and water plants. Kerner suggests that these hairs serve to keep water out in wet tines. Glands as in rose-petals. Kerner suggests sticky hairs prevent insects and ants climbing up stem, or another theory that they give help in their moving up and down. Lothelisr--on spines. From examples he says drouth produces spines, but dryness, noie. Also they have beon developed by different conditionsf food and nourishmant. 2. Waxy coat or bloom. Regarded as naving a protective function. 3. Thick skin, Clearly a protective function. Such plants found most plentifully in Arctic and Alpine regions, also in places of annual rains. Hairy forms found chiefly in desert regions. Thick-skinned leaf more transparent than hairy. 4, Succulent leaf. Most extreme of all types. Have very thin skins. Some will hold their water for several months even near fires. 5. hessened leaf surface. 6. Vertical position. 7. Leaf movement. 8. Poisons. Modern view is away from protection--Case of Nettle--here Sting is undoubtedly for purposes of protection. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Yogev 6 osnensnnsntionti LO so 59 . Many plants seem to have no protection but grow in vositious where they can be away from danger 5 others seem to grow utterly “unprotected. 2. Protection during transition. Buds--by scales, hairs and position in bud. At this time (transition) we find also greatest development of color... leaf movements. Development of seedlings. Sesdcoats, movements, bendings of stems, scales, hairs, ete. 5. Protection duping rest period. This is highest development. Crisis in life a tree, usually the season of winter. Duckweed--large cells or air spaces which _ serve not only for storage of air but also for purposes of buovancy. In fall a bud comes out without the cells and falls to the bottom where it remains during the cold pea. Annuals.. Perennials. On land have various ways of protection. Rosette form during period of rest and erect stem during period of vegetation. Corns, bulbs, tubers, rhizoids. Trees themselves with deciduous leaves. Evergreens. Why is a tree ? Question of erectness--a necessity of Light. Question of woody stem--duration and economy. No form better adapted to extreme xerophytic conditions than a scedie modification of the tree type, the barrel-shaped tree with immense development of storage tissue. Yuccas on our western deserts. Pirst trees were Pteridophytes and Gymnosperms. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, N.Y... itihae Mma 60 Ancient treas, Lepidodendrons---like Cycopodiums, Calamites---like Equisetiums. Ferns proper. Gymnosperms. The first two are distinctly xerophytic in structure, hence the question whether tie original trees grew in deserts or tropical wet regions. Deciduous versus evergreen, Drouth and cold, alternating with moisture and heat produce deciduous trees. Uniformity of conditions produce the evergreen. Exceotion to this evergreens which increase towards the north. One reason is a advantage of being reaiy for work at ali times without beginning again. Power to resist sudden changes as summer frosts. Sclerophyll or hard-leaved type, as laurel or holly. Needle-leaved or northern types. Soft-leaved or southern trpes. The first is fitted to resist unfavorable conditions, as cold and rain together and drouth and heat ; hence this type of plant is largely developed in Mediterranean region, in California, along the Gulf coast, etc. This leaf a kind of half-way condition. ge Light. Vagetative Reproduction. Protection. Tree, deciduous tree. TPee, evergreen---needle, tropical, hard-leaved. Lianas. Rhizome, Bulb, Rosette, Annual. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. 61 Lecture 14, August 1, 1900. *%. Bibliography of Long*Isiand. Mather : Geology, Ist Dist, N.Y. 1843. Upham : Terminal moraines of North American Ice Sheet. Am.J.Sci.T, /f, Merrill : Geography of Long island. Am. N.¥. Acad. Science, TL, Wav, 7466 Hollick : dretaceous Formation of Long Island. Jeliiffe : Flora of Long Island, 1899. Long Island. Long Island. 120 miles long and from 10-20 miles wide. Two distinct parts. Northern, hiliy, southern flat. Hills begin at Bay Ridge, extend to Roslyn, N.E., then east to Sag Harbor-and thence to Montauk Point. Vallevs extending across narbor from tne bays ; fewer streams than valleys on north sijee!* 86 valleys have be4n counted. On the south shore vallevs probably remnants of old glacial stremms. No lakes or rivers on the island, but many springs due to fact that upper soil is sand and gravel preventing surface drainage and under layer of clay. Hence drainage of Long Island is like that of a limestone region. Few ponds, but many swamps. Ons lake, Ronkonkonia--3 miles. Many indentations on north shore, irregular coast-line made more irregular by post-glacial action as at Lloyd's Boint. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, AND, Wisp scecnaeeneeet asichin ss cermin 190... Historical Geolo:-. L.udArehaeans-Crystalline--found on western part of Long Island-- ie TF gts Astoria and Hell Gate and Long Island City. In Brooklyn such rocks have been struck by Artesian wells. Chiefly gneiss and granite. These rocks have no influence on flora. 2. The Paleozoic and early Mesozoie unrepresented until we come to the Tertiary and Cretaceous represented by the clays underneath the drift. In the south the soil is entirely so. Yellow sands and craveis.' age unknown. Merrill's theory that these deposits represent an earlier glacial epoch. Whenever this gravel is in contact with drift, it is always below it and always above known tertiar: deposits. The present cofastal plain of Long Island was see much more extended, out to the hundred fathom line. Buried rivers in this vicinity, as Hudson. At close of cretaceous period, probably Long Island was. continuous with New York. New Jersey and Mass. separated from Conn. “by @ fresh water stream. Soil probably slacial on north side and boundary absolutely distinct between hills on north from plain on south. Hills average 250 ft. in height. Highesr hill, Harbor Hill, near Roslyn, 391.ft. A second moraine on north coast gives its shape to the coast. ere these two moraines is a plain, well-marked. Terminal moraine stops ona southern slope--this positive proof of glacial advanc:. South slope probably was an overwash from the glacier. Glacial clay or till, pest deposits in Brooklyn. Sands and gravels in Kames, in other parts. Also boulders of gneiss and granites. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, No Yj cece oe Tagory of these Hills. Kame theory. Merrill's theory--fold ed strata always in association. with bays, hence he concludes that the glacier scoured out the WYQQS/ bays and pushed up the hills at the sides. Evidences against this theory. In post-glacial times, we find the most important modifications upon our flora. Wearing away of east end and deposition along the south shore, besides local changes which form the important relations in ecological study. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthacea, Ni Voy crrcccssssnnereiscnnnein s 64 Lecture 1F, August 2, 1900. Phys iographic Eeolosy of Long Island. 3 phases. . 1. Plants, organs, and their ecological relations. 2. Plant societies and their ecological relations(locallr). 3. Climatic ecology or geographic botany. (Puytogeography). Western prairies explained by climatic differences. ‘Edaphic as (local in character) opposed to climatic. Such factors as have to do with zonal distribution, springs, slopes, etc. Ecology used since 1895 when it was introduced by Warming. Three distinct phases given above. Physiographic ecology deals with relations of plants societies to their local environments. ‘Two distinct units in such a study. Leg Topographic form, merely a stage in development of a region. >, Plant society an assemblage of plants in a common habitat. Also a stage in the development of a region from the plant's standpoint. Physiographic Ecology has no histiry, since this may be termed the prehistoric time. Begins really with Warming when he published in 1895, Greatest work since then that of Schimper, in 1899. Other - papers have been published. Edaphic Factors. ‘1. Water. Water level always modifies flora of a region. fhydrophytic soil 80%. xerophytic soil 10 % mesophytic, between the two GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, N. NZ ctameecesp las rine, = abiundiereentan Gate tes I90...... 65 ‘Importance of water from its variability and uncertainty. One of great causes for difference in water is difference in soil. Another, evaporation ; others, openness of soil and slope. Soil water is an edeYphic factor. 2. Light. Sunlight both edaphic and climatic. Zones of the earth divided pecause of light being distributed differently. Ina forest difference comes from the influence of light as an edaphic factor. Succession of forest trees ; first aspens, and white birches ; then pines, then oaks and lastly beeches. ‘Such succession found in Michigan caused very largely by difference in light. First are light-loving trees and they grade down to those which can grow in shade. Other influences of light. Suggestions in water plants, as different colored Algae. 3. Heat--most important climatic factor from north to south. Of ‘comparat ively little importance as an edaphic factor. Difference in temperature of soils. (A) Slope. (B) Amount of water. Do not look for early spring flowers in a swamp. It is too cold and wet. ‘4 Air. One of the most important factors, but not ecologically because of its evenness. iovements often radically change the flora of the region. Importance of air in the water. In stagnant water plants have been unable to get proper gaseous food through the ordinary channels, hence ee ee to adopt extraordinary methods like the ' Utricularia, GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Vij vec i tees reeener LGD, Go Lectur? 16, August 6, 1900. be Soil. Schimper considers soil most important factor but Be includes every- thing under the fave Beli Which is contained in it, as water, etc. Soil ecologically is that in which a plant can grow. Soil is divided mechanically into 1. Solid rock. Difference in flora in this case depends upon character of rock. Different types of lichens grow on granite, limestone, ete. Tichens a real rock plant, mosses grow more in crevices. Shaly rocks decay so rapidly that lichens find it difficult to grow on them. Sandstone varies. Granite allows much growth of lichens since the feldspar in it erodes more rapidly than the other elements and gives foothold for the spores. 2. Residual soil. Not found in glaciated regions, hence not found in Long Island. 3. Secondary soils. | Soils which begin as residual soils but are transported to bodher places. Hxample--Fire Island. All the soil secondary, probabiy came “from Montauk Point and before that from N. E. Such soilé represent erosion of rocks ages ago, either by water action, wind action or glacial action. Deposits strictly due to glaciation are usually ‘unstratified. Those due to water stratified and coarse. Those due to wind fine and stratified g¢4f or unstratified. Bulk of Lone Island ‘deposits may be ascribed to waters which came from melting ice GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, N. Vora priveses dace sane stone EGO. 67 [Becondar-” Soils. (a) Sand including gravel. Sand is almost the opposite of clay. It is porous, but its food value is poor because of ite make-up. Sand is made up of particles of almost insoluble minerals as quartz. Water percolates througn it so rapidly it has almost no cohesion and no water capacity. It heats and cools with greater rapidity than other soil, hence it is most xerophytic of soils. (b) Clay. Heterogeneous soil. Most northern clays represent pulverized rock left by glacier, Chief element Alg (Si Oy 3), Clay may or may not be rich in food stuffs, according to its origin. It consists of more soluble materials and retains them. Smaller ths particles, less the porosity. A swamp is never found on a sand hill but often on a clay. (ec) Humis---a soil derived from decay of organic matter where there is not complete oxidation. Better than sand or clay aang and ‘also because it contains soluble avids. Plants require a certain ‘amount of inorganic substances. Presence o* absence of water largely determines presence of humis. Three kinds of humis : mould, peat, sehlaum. ‘Schlaun is entirely formed below the water. Organic mud. Color of soil depends largely upon the amount of oxidation. Blacker and finer humis, better the soil, as ina forest. Underground animals add greatly to the value of soil, as earthworms and bacterin, Peat is charavteristic of a northern climate from coolness and moisture Recent studies show that physiographic youth of region also determines the formation of peat. Best explained by absence of oxidation and QEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthata, No Yoyo 2 8 iwhine taeehGe es 68 drainase. Few bacteria in swamps. Too acid to raise many plants. Forests--evergreen, tropical forests highest development of plant kingdom. Richer the Co ee the humis. Accumulative effects in a forest. C. and N. are gradually increasing in a forest soil. (d) Mixed soil as loam--either humis or a mixture of two or three elements known as mixed soils. (e) Caleareous soils.-~-marls of N.J. coral soils of Permuida. (f) Salts sbils. Salt semms to produce 4 xerophytic form of plants. Chemistry vs. Physics of Soils. Which has more effect upon flora of the region ? Abrupt changes in flora from one strate to next. One theory, the chemical conditions of the soil. Unger. Thurman, on the contrary, held the view that the kind of soil ‘decides the flora, whether it is dry or porous, etc. Warming accepts the physical theory in most cases 3; but excepts halophytes or marsh plants. Schimper inclines to the chemical view. Dr. Cowles considers the chemical view the better. Nageli called attention to strugele for existence 3 that chestnut grows in sandy places not because it likes it best but because the beech crowds it out by occupying hetter places. Another factor is cag guwelonneenas age of region. The true theory is probably that of a mixture of all four. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Tthaca, No Voy enrncnn cinerea : Field Work. Jule 275 L700. Drawing. Regions 1 and 2 represent the xerophytic side of the beach ; 3, 4, and 5 the hydrophytic area. Under the water was eel-grass in great quantities. From the water's edge to high tide was no vegetation owing to the instability of conditions. Region 1 might be called the gone of annuals since it was covered with water part of the vear. The perennials would be those which had grown this yvear. Plants in Region 1. 1, Salsola Kali Saltwort. 2. @henopodium album Lamb's Quarters. 8, Cakile Americana Sea-rocket. -4, Polygonium Convolvulus Black Bindweed. (5, Xanthium Cockle-bur. (6, Atriplex hastata Orache. 7. Anmorphils Sand-reed. 8. Oenothera Primrose. 9, Strophostyles angulosa ‘LO. Rhus toxicoderidron Poison Ivy. ll. Solidago sempervirens, Goldenrod. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, N. Yu... l2. Bidens frondosa Beggear-ticks. 13. Stromonium (Datina) Stinkweed. 14, Panicum sanguinale | 15, Taraxacum Dandelion. 16. Ambrosia Ragweed. The most typical forms are Salsola, Cakile, and Number of indiwtiduals of each species were small. Region II was characterized by biennials. 1. Ammorphila arundinacea. 2. Salsola. 3. Aanthiun. 4, Cakile. 5, Panicum sanguinale. 6. Solidago sempervirens. 7. Erigeron Canadensis. Horse-weed. 8, Marrubrium vulgaris Horehound. 9, Asparagus. (10. Linaria vulgaris. 11, Achillea lfillefolium Yarrow. 12. Lathyrus maritimms Beach pea. 13. Nepeta cataria Catnip. eld, Ampelopsis. (15. Plantago lanceolata. ‘17, Sweda linearis Sea-blite. (18, Atriplex. 19, Oenothera. Xanthiun. 70 GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. Ithaca, No Yoyo Deen: He 71 20. Bidens, 21. Chenopodiun, 22. Tactuca Lettuce, 25. llollugo verticillata Carpet-weed. 24, Ailanthus glandulosus. 2i. Rhus, 26. Malva rotundifolia. This zone might be calied the Anmmorphila zone since that plant predominates. The nexr most prominent plants were Solidago, Rhus, and Salicornia. Plants of Region III. Cakile Americana. Solidago sempervirens Ambrosia artemisiaefolis Oenothera sueda Salsola, Atriplex. This region was narrow extending from the é@dge of the summit to the winter tide mark. Cakils predominated and there was a good deal of Sueda and Salsola. ‘Plants of Region IV. This might be called the Spartina juincea sexian aiage that plant occupied the largest space. With it was ? Statice (var.) Caroliniana. Salsola Kali. Atriplex. Sueda linearis Region V. This zone was completely covered at high tide and showed a growth of Spartina polystachya. GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY. ‘ Ithaca, CIN VE Bo mere cornea TQO ai Z swamp Veretation Brash Water. 1. Goodyera pubescens Rattlesnake Plantain, 2. Habenaria tridentata 5. Botrychium dissecta 4. Botryciium ternata 5. Osmuinda cinnamomea 6. Osmunds resalis 7. Pteris aqyuilina 8. Woodwardia august ifolia 9, Onoclea sensibilis 10. Dicksomia punctilobia ll. Aspidium Thelypteris 12. Vaccinium corymbosun Tall swamp bluberry. 15, Carpinus Water beech, Betula lenta Sweet bircen, 15. Viburnun dentatum 16. Nyssa sylvatica Sour fm. 17, Rubrus hispidus mvergreen blackberry. 18. Viola hblanda 19. Viola prunvfolia 20. Chryvsosplemim Americanum Golden Saxifraze. 21, Inpatiens viva 22. Alnus ineana 26. Kalmin latifolin 24, Elodes campanulata larsh St. Johnswort. 20. 29. 30. SL. Bes 33. 3h, Acer ruvrun. S milax rotundifolia. Andromeda ligustriuaa. Arisaema triphyiluia. Symplocarpus foetidus. ‘Hamamelis Virginiana. Drosera rotundifolia. R C osa Carolina. lethra alilmifolia., Polygonium Convolvulus. Polygonium arifoliun. Polveoniun sagistatum, 37. 58. 40. 41. 42, 43. IMedeola Virginica. Tridentalis Americana Chickwesd, Wintergreen. Vv Dm de itis Labrusca nus venenata Rhododendron viscosa Azalea (False Honeysuckle). Northern fox-grape. Hydrocotyle Americans Water veiuywort. iE yrola rotundifolia. eo) Ley] 74 Auimist S, 1900. Ocean Reach at Tire Islaad, On the south shore the land is being slowly built up. Tunes have been formed, but owing to the variable character of the winds the dunes do not attain the height of those near Take Ilichigan, Several zones may be distinguished. “ T. The Ocean Beach Zone. II. First Row of Dunes. III. Inner Dunes, , es Anmnophila region. “Yb. Hudsonin region. IV. Swamps in the Dunes. V. Low Dunes on the Bay Shore. VI. Beach Zone on the Baz Shore. No vegetation on the ocean beach owing to the disastrous effects 2 ahs 5 gee Aet of strong surf and high winds. The shape of the first dunes is ‘like this (drawing), not the usual dune shape since the dune has al q received a cliff-like aspect from tie vigorous wave action. Th direction of the wind being variable the dunes as a whole are not ” moving, thovgh there is more or less sniftinzs of the sand. This sand was purple in some places and Was mixed with garnet particles as well as magnetite. Il. First Dune Recion. Ammophiia. Lathyrus maritimus. Cakile Americana. Oenothera biennis ‘ Solidaso setupervirens. buphorbis. polveonifolia. The inner dunes were the highest on Tire Island, and most nearliz: approsxcn moving dunes. They sluowed two characteristic zones of vegetation ; first tie Amuocphila zone where that plant was found in exposed situations where the life struggle is most severe. Second tne Hudsonia zone. In this Hudsonia grew in more protected places, especially on the north side of the dunes. Other plants of the Hudsonia zone were : l.Lechia maritimes Pinweed. 2, Carex straminea 3, Urperus Grayii. III. Plants of the Swamp Regions growing in depressions. 1. Discovleursa capillacea Boneset. Z 2. Evpatiorun perfoliatuns” 3. Lycopodium. “4, Sabbatia stellaris 5. Spartima juncea. 6. Potentills anserina. 7, Panicum dichotomum. ' 8. Viola lanceolata. 9. Polygonum acre. Water Stuirtweed. 10. Erechtites hieracifolix Fireweed. 1l. Solidago teimfolia -12. Oenothera fructicosa (var. humifosa). 13. Polwsola verticeliata. 14, Spiranthes praecox. 70. #15. Hibiscus Jloschentos Rose-ilallow. 1é, Pluchea camphorata “Camphor-plsant., 17. KAlimia angustifolia 18s Hide lutun smereearped Targe Cranberry. 1%, IPiss 20. Iva frutescens. -These depressions scattered among the dunes sre undrsined swamps. They are probably rennants of the se. which being cut off, formed lakes and. finally became fresh water marshes. Ve. and VI. ow Dunes and Deach on the Bay Side. Here the flora was essentially like that of the sand spit, xeropnytic in character. 1. Cakile Americana, 2. Saisoia “Ali. ‘3. Kantinium Cockle-bur. 4, Atriplex arenaria Orache. 5. Euphorbia polygonifolia. 6. A few Ammophila plants. 7, Amaranthus pumilis Pigweed. 8, Arenaria peploides Sandwort. The future of Fire Island seems to be occupied hy forests. The following seedlings were found ° ‘Pimis rigida. Betuls populifolis. Populus tremuloides. iMyvrica cerifera. Juniperus Virginiana. ve Plants found in hlarsh at Bab-ion. Eloides canmpanilata Marsh St. Johnswort. ;. Habenaria blephaririottis White fringsed-orchid, EN ae ee Necture 17, Ausust 8, 1900, Classification of Plant Societies. Drude's Handbook of Plant Geography, 1090, purely georraphical. Enzl3r and Drude : Vegetation der Mrde, to be in a hundred volumes only a few having now been published. In 169% Warming--Danish--published "Plantes amfund." In this the classification based on the water conditions of the soil. In eee 205 shane aS as his principal classification, in dividing the world, heat. Torrid, temperates, Arctic, i'tountain and Water. Warning 's i@ a classification in the small, Schimper's in the large. The latter divides each of his zones as forest, crassland and deserts, which are determined by climatic causes. Peat bogs, dunes, atc. are determined by edaphic causes. Nilsson and other Scandinavisrian writers sre working along ecological Lines. Graebner in 1898 published a pamphlet which classified according to chemical food stuffs of the soil. In attempting to place the flora of North America according to Warming's classification, a difficulty is found in peat bogs. Tue real trouble of Warning's plan is that he bases all uponofie factor, water. 76 Dr, Cowles’ Theory of Classification. 1. That nature is dynamic not stactic. 2. That the presence of plants depends upon the topographical con- ditions of the place, almost entirely. As a region gets older, tne topography ias more and more to do with the flora, and the geology, less and less, 5. Topograpuy depends on dinamics, not statics. 4, That plant societies ure made what they are largely by past influences, since the vegetation lage behind the topogravliv. kKesult of accumulative effects. Tue vegetation of any district is a complex resultant of past eni present. Accumulative effect of environment shown bz: the. inecresse of humus. Bach plant society by its own existence prepares the way for its own downfall and its replacement by something else. Hence there mist. he definite suvecession of plants. A sanetic lassification such as this is based on relations, Peat bors and a wm Ke i -heaths are fenetically connected. Toposrapnic Changes, Two grest agencies at work in 4 revion, demidation and deposition, affect of such processes, since highest hills most eroded andi highest valleys less filled up, is planation. A hill necessarily must he xeropivtic and a Walley hydrophytic ; hence as planation increases, the ultinate end of all plant socitties over inland areas where climate is favorable, seems to he to reduce all to mesophvtes, Crustal movements also have to do with this classification, Atkinson's v. 374-425, Coulter's Plant Relations. 79 Stream Veretation Avsust 8, 1900. Vegetation along a flowing streai changes very much fron various causes, Chief among these is the drainage whether the stream flows rapidivy or slowl:. Another is difference in the depth flora. wiich sometimes grows to the verv edge of the water aud still anoyher the difference in temperature. First Region. From the spring where the stream flows iors rapidly. Around thie source we found a quantity of Sagina procumbens which always grows pest in a cool, shady place, Sagina procumbens. Lycopus Virginicus. Kupatorum purpureun, Joe-Pye weed. Enpatorum perfoliatum, Boneset. Viola cucullata (with cleistagomous flowers). Impatiens fulva. Alnus. Symplocarpus foetidus. Chrysospleniun, Golden Saxifrage. Second Region. Where the stream began to slow up. 1. Sphagnum. 2. Rubrus hispidus. 3. Viburnun. 4. Apios tuberosa. 5. Polygonum arifolium, Halbert-leaved Tear-thumb. 6. Polygonium sagittatum, Arrow-leaved Tear-thumh. 7. Osmunda, 8. Glyceria nervata, grass(fowl meadow). 9. Epilobium coloratun. ‘10. Carex intumescens, sedge. 11. Scutellaria laterifolia, Mad-dog Skullcap. 12. Chelone glabra. 1S, Galiua trifidum, vars, latifolium, Small Bedstraw. 14. Viola blanda. 15, Hloides canpanulata,. 80 wey ahixrd Kerio. Where the stream flowed throvgh open meadows. 1. Pilea pumila. 2. Polygonfiin Hrdropiper, Water-pepper. 3, Onocles. sensibilis. 4, Carex. 5. Scirpius. 6. Inrcopus seminatus. 7. Ludwigia alternifolia, Seed-box. 8. Mentha viridis, Spearmint. 9, Mentha piperita, Peppermint. 10. Asplenium Filix- foemina. 11. Hypericum .iudicvants, Orange-grass, Pineweed. 12. Houstonia. 13. Polygonum Pennsylvanicun. 14, Vernonia. Along the wood road grew AnAphalis margaritacea, Pearly ever- lasting. In the stream was ltvricophyllum tenellum. Lecture 13, August 9, 1900, I. Progressive Series S Le matress. Poverty to wealth. A. Towards water level Xerophrtic to Mesophytic, 1. Hills a. Chemical and Physical NAture. 0. Direction of Slope. Crustal movements may have the sane or Opposite effects as physiographic factors. An upward crustal movement in 4 swarp will have the same effect as the physiographic. A country-s development may be traced from youth to maturity, as well as from poverty to wealth, a condition due to the accumilation of We nunis. The Flora at the start on a hill or mountains mst he xerophvtic. Erosion is always tending to wear a hill down to level, rotnding the edges first. The slope being different, by drainage changes, the rocks are worn into finer materials, and as plants die, humis accumlates. Changes in shape bring about different conditions for plant Life. The principal changes will he ‘Ll. Less exposure. 2. More water. 3. Finer soil, 4, Accumulation of humis. From these differences vegetation will soon change from xerophy- to mesophytic. In digging through a hill we find the water level, no sudden changre, but the amount of water in tie soil gradually inereases as we pass downward. | Hills (a) Chemical aud Physical Factors. dl sand and fravel. (Kames--glacial). With racard to the nature of the soil Kames are the same As sand &2 dines, except the particles are larger, sud the develourent of vegetation is probably the same. Kame flora probably originated in glacial times. If a Name covld be denuded we would find tue same successtén of flora as that on a beach, On a sand hill there is a long period between youth and maturity hecause sand does not readily retain water and humis accumilation is slow. o. Glo Bilt is just the opposite, and also erodes more rapidly. On the hills in this region chestnut oaks and chestimts are ffow the most dominant trees. Pinus rigidus was probably the first, followed by Quercus nigre and Castanea the first of which was replaced by Robinia. It is difficult to determine wnat the future will he. Beaches and maples are xerophytic and are found to some extent at foot of the hills. They represent a later stage than the chestnut. 5. Bock Bilis. Lichens are the first plants found on rock hills. Granites are best adapted to lichen growth since the different constituents decay unequally giving rise to crevices which allow the plants to gain a foothold. Limestone and sandstone are less well adapted owing to their rapid disintegration. Lichenus are .followed hz crevice plants especially mosses ané some of the wilnies, B. Direction of Slope. Tie sun is such an important factor that in spite of tie direct ion of prevailing wonds, the north slop? is alwars the moistest. Moisture and wind are most important factors in determining the slove of a hill. 63 C. Altitude, (a) Absolute altitude is height above the sex level. (b) Relative altindéeis height above the surrounding country. The first has 4 strong effect and gives rise to distinct zones. It shows especially over creat heights while relative height effects smaller areas which differ slightly in altitude.** In three hills of 200, 400 and 800, the vegetation will be about the same, being: exposed to about the same conditions unless protected by other hills. In &@ hill in the latitude of N.Y. the most xerophyvtic plants will generally grow on ae upper parts of the north and soutn slowes. Tie north slope is xerophytic because there is less heat and an. increased exposure to colder winds, while on the sovth the sane condition@ prevail, the soil being drier on account of the greater amount of heat. Hast and west slopes will be oe mesophytic. In the latitude of Georgia the south slope will be the hottest and driest making it most xer@phytic ; while the lower north slope will be most mesovhytic owing to the greater amount of moisture, the latitude being such that the least supply on the north side will be sufficient to produce a mesophytic flora. In the forests of Canada, a xerophytic forest is usuali:v due to the absence of heat and not to the ubsence of moisture. Hence the/most portion of + in this case xerophytic hill will be the upper part of the north slope, since that region is most exposed to the cold. The lower part of the south slope will probably be mesopnytic, due to the increased heat. on Ve ms D. snvironment. 1. If 4 hill is surrouuded bv: other hills, a mesophytic flora ms often be produced. A hill protected by higher hills way have a mesopiytiec flora to the top. In a V-shaped valley the flora will probably he mesophytic being protected from excessive heat, wind and cold. While the slope tends to make the soil drz, this will be counteracted by the absence of strong light. When erosion changes a V-shaped valley to a U-shaped one, one side will have a mesophirtic flors, the other side protecting it just as hills surrounding it may protect another dul dole Two factors tend to produce 4 mesopuytic flora on hills, 1. Tne physiograpnic changes of tne hills. 2. The accumulation of humis. This is beautifully sii in the White Mountains where we have a mesophytic flora hefore a base level is teached. On the otner hand, on the seashore or desert, we may have base level without a mesophytic flora. II. A hill exposed to ocean action must remain xerophytic as long as the ocean romains, so will have a xerophrtic flora in a mesovhrtic climate. There may be 4 mesophytic flora if the ocean has encroached on the land bringing areas formerly removed from water action to the coast. In order to have a mesophytic forest, there must be 4 great amount of atmospheric moisture. lecture 19, August 13, 1900. 2. Aerophytic Beach. Found comaonly along exposed shores ; leust marled i: harbors. BX. Fire Island. 1. A case where beach is encroaching upon the shore. a. Below low tide complete submergence, flora iot xerophytic. On a protects] beach, flora is b. Below high tide. Aiternation of submergence and drv land. Hera we find xerophytic plants forms of Algae. c. Lower beach from high tide line to that of highest summer storms. During most of year conditions excessively xerophytic, preventing water forms, while the occasional submergence prevents xeroviytic types, so this is a desert zone. In very wet seasons and in spring Algae sometimes grows here. ad. Middle beach from limit of summer to limit of winter storms. This is quiescent in sumier, hence Annuals can grow there. Salsols, Cakile, Xanthium, etc. e. Upper beach or fossil beach, above line of storms, so-called since it once was a beach, Here perennials may grow. Ammophils, Lathyrus, etc. f. Dunes. A wind-blown structure while heach is wave-produced. Dune sa:d more uniform and finer than beach sand. Heavier elements. not biown up 6 form dunes as seen in the garnetiferous and magnitite sands on the beach at Fire Island. 86 Beach conditions extreme in every respect: 3 on dunes, same conditions, and also those of demidation and burial. Am.ophila indirectly; one of the most commercial plants in the world being a ‘sand-binder. When a dune gets very large, the conditions becone very bad for Amuophila and the plant dying, the wind has full power over the sand hill. After Ammophils comes the shrub zone, Pruss maritanus, Ibrrica cerifera, Rhus toxicendendron., Tree Zone follows the shrub. Juniperus Virginiana; then pines and oaks. (uercus nigre séems almost as resistant as t19 pine. A characteristic undergrowth accompanies each kind of tree. Humis is being increased. Xerophytic heach easil: told from desert stretch while on hydrophytic beach the vegetation presents an unbroken series. Why is this difference ? 1. Difference from exposure (seen on Spit). oe Sieve Fe Slope, that of werophytic being more rapid than hydrophytic. 3, Hydrophytic beach more coumon where springs enter. Exposure the predominant factor. Shingle or gravel beaches xerophytic since there is little-’chance for accumulation of humis. B. Away from water level, 1. Drained swamps or rivers. 2. Undrained swamps or kettle holes. 3. Hydrophytic shores or salt marsh. 67 I. Rivers, Two elements &. Changes in climate and altitude. b. Influence of physiograph: on the river/flora. In @ typical river there are four stares------- Miss. River. 1, The ravine stage. 2. The U-shaped valley. 3. the Foof plain, 4, The Cresecentic lakes or Ox-bows. Flora ii 411 regions very different. The beginning of a river is retregressive. If a river eats back in a wooded country, we. should find a ravine flora replacing the forest. Great area of rich soil deposited by the river in its constructive stage. In the destructive stage, the flora will retrogress ; in the constructive, the progressive stage. 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