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ALBERT R. MANN LIBRARY AT CORNELL UNIVERSITY
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Cornell University
The original of this book is in the Cornell University Library.
There are no known copyright restrictions in the United States on the use of the text.
http://www.archive.org/details/cu31924003517285
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 anitials.
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 meiccizie hypothesis calls for every possible xplanation 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.
Lthatca: Ns vg sscceesceceesecconpeiee atten) omer 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 = CHO + Q, 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.,
+S) 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 protoszntax. 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 jesse sons er 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.
Tthatt,, Bl 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.
Chlorophyll 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
I QGO
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
ean 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 funettons 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 Vuyeecon on
ie
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 to. OF. 22 plants out of 27 carry on the work of aeneraeedian at that temperature. =
Many plants must acquire means for protection against extremes and sudden ehanges 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 Hy 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 o-
AiR se
Winds have great influence on plant forms, and on their dis- trivaddion, 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 ¢Y¥¢f 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 consequent dryness.
Leaves and branches are often less developed on the windward
GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY.
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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 teeande 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.
in aeraues 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:vsen. 2. Fertilization of saute 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
Ze 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.,
j {—!
Lecture 4, July 9.
Water.
Water is one of the necessary elements for plant life. Plant structure and cell sap both contain mich 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 earried 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 ap 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 Littie 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, DF ecncteciecemersspaee 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 callel 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 oem ie 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 symbiasis, 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.
Te a see caearbed
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,. Ewission of liquid water from so-called water structure.
GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY.
ee a ee ee
- (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. hb. 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.
fot ae, ae eee ee ny 7.)
17 19. Heredity. The grass and sedge form, (ebongation, verticality, narrowness) typical of a marsh plant. Algae.
Red Algae frow lowermost, green next, and brown nearest shore. Water lily shows red on lower surface, Question of color. Fucus 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.
Tne 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 cece 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 Saeene 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.,
190...
19 Lecture 6, July 17, 1900.
Kerner's Light Theory. Dist.
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 gr
) @O rs
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 sphericsi form has smallest surface. All gradations between greatuess 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 Equatog--varies as we come further north.
GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY.
Tthaca, No Vy ccc cen £90...
20
Verticality.
If a leaf faces north and south, the south 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
v
GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY.
That, le Vgc ane = eee «en
al
In general densit: of arrangemeit is dependent on aia 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 phylhotaxy, 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. a- 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. sieceaie 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
25
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...
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becture 7%; Jute 16, 1900,
tiene (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 J¥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.
Tthaca, No Voy cece ono . £90...
24 adapta$ion 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 ;
PAY 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 toe 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 CO ; 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 Vy cece oe Ll 9O..,
ae stagnant water. Here small quantities of 0 is presant and animals obtain most. From study of water plants it has been shown that large spaces for air always exist. Need for O therefore modifies water-leaf.
Emission 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. heed 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 Yegencieckiicnesons : Le eel 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 environment than other families because it can work at day 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 PEG 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 greater the current, the greater gmount of salts earried.
GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY.
Tthaca, IN: V gy c0cdisccesssssecs si) LGB
27
This was old MGARAIOHC Siew. Now it is eswant 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 tine 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 hyfrothodes 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 lieaves are lowest. It may be because
GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY.
Tthaca, No Vij cece ces ee: ae
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.
11. 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 veces 190...
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 sAys 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.
1s. 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 environuent. 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.
Tthacar, No Vi, paces Pe oan 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 become fixed in time and when plasticity is once lost, it is lost forever.
Read ing--Coulter--Dhap. IV.--Shoots. p. 53-88.
Field Work July 18, 1900.
To study development of leaf teeth, use Viburnum, Red Oak, Chestnut, Circaea, Sycamore. Examples 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, a 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.
dthaca,. No Vise ccc — . 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 Rave become 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.
nd
study of Leucobrvin. Celis connected by pores. Three layers, with chlor. in the central one. Air cells on surface guarding chlor. 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 sone 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 cocci in
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 t Same fungi cause nodules on Lequiminosae.
Cladoma, Reindeer lichens.
GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY.
Tthaca, No Vy serene oe. GOL.
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 heach 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 Sie: eats 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 that 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. Oenothera, Evening Primrose.
6, Salsola kali, Saltwort.
GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY.
Ithaca, No Yoyo 2 £90...
wa ee
7. Solidago sempervirens, Goldenrod.
8. Atriplex hastata, Orache.
9. Huphorbia polygonifolba, Spurge.
10. Lathyrus maritinus, Sand Pea.
11. Strophostyles Anguilosa. 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 sienbey
Silisola 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 mueh 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 Vij eee
Ssalsola kali, Salitwort.
and 7, 3, 1, 5, 9, of the list of annual plants ; besides
10.
di dg
LAs
15s
10.
besides 10, 7, 6, of first list and 10 of, the second.
Rhus toxicodendron, Poison ivy. Helianthus, Sunflower, Arenaria peploides
Atriplex hastata, orache.
The third plant zone is exposed to less xerophytic
Plants of third zone. Amophnila, Sand reed. Prunus maritima, Beach vin. Asclepias cornuta, Milkweed. Rumex acetocella, Sheep sorrel. Lenaria vulgaris, Butter-and-hegs. Verbaseum thapsus, lullen. Myriea cerifera, Bay berry. Artemesia candata, Wormwood. Chryvsopsis falcata, Golden aster.
Artemesus stelleriana, Dusty lfliller.
conditions.
Lathyrus shows sleep movements, its leaves assuming lateral
position during the day, thus preventing transpiration. Ammophilsa
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 hydrophytic. 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 mada 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 essentially 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. Uathyrus. 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. Irrica cerifera. Not found on the Lakes. Sg hideca i seenaeetnenk, Fs %o bapkeeod. Prunus maritimus, N.B. to Va.
Artemesia stellariana, L.1. 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 mist become filamentous, expanded, or show evolution of an internal atmosphere. Adaptation of form to external environment in lower forms; in higher also accommodation ae 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! Sigg oi Greripesccereeosas ft asses SB
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 examples of which are found in the water. Size in eontrast to form seems to be largely a matter of food supply. Sometimes form may also ve modified by food-supplr. In determining direction and arrangement 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 ravs 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 Voy eeccccc Sn 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. Anthwoeyan, 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,
Q@EO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY.
Ithaca, N. Y.,
40 5. Another objection is that tropical plants show the most cole:
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 Outline. 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, WV,
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 es 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 in a 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. ih famed the light relation is insignificant. Another theory is that carrying a plant above the ground favors reproduction, spores or poilen 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 lignt.,, Tree ferns and Monocotyledons have no
GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY.
.. Ithaca, N. Y.,
40 petioles or branches. While in Dicotyledons there is great abilit: for branching and leaf display, the stem gives nothing to — plant but mechanical support. In some plants it may be 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
celis are dead. Exception, the birch. There colors are probe#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 Shelli bark Hickory. Betula lenta Sweet Birch. Prunus serotina Wild black cherry.
' Prunus cerasus Cultivated cherry.
Robinia pseudocassia Tocust. 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 Voy soscccrarcnpige 4 oo were T90......
Vaccinevum 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.
forests,
“ Vaple-lea
Dwarf Blueberry. Service-berry. Poison Ivy.
ved. Viburn um
Witch Hazel. Spice bush. Locust.
Virginia Creeper. Summer Grape.
Bay berry.
If found
in
ae
it probably dates back to a time when the land was treeless.
GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY-
Ithaca, No Yor nevro 190...
45 Field Work. July 25, 1900.
Cooper's Bluff.
The bluff was a steep, sandy slope extending down to a flat peach. 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 appeared 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
s Mune 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 really three regions, showing some differences in the
flora ; the bluff proper where were found
had ; Trifolium &rvenses|-> oA = nh / 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 Iva.
Grass.
Bayberry.
GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY.
Ithaca, N. Y., eluate aaa aN ess gt 790."
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. Ltanas. re
Bey
Tne philosophy of stems. is really the philosophy of fico 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, paRiaiee, shend, etc.
Lianas ee eee 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 eratnae 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 piand, 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 Vij eorg:
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. ‘ 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 permanent 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 ee ae
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 pesy made.
Uses of stems.
1. Display of foliage and flowers. 2. Vegetative reproduction. Yertical 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.
Dthace IN Voy weietiscencoumonnien 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. inp 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 5; 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 rhizoids of mosses
“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.
Ithaca, 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 Beda 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 ampaniee matter. Many fungi are saprophytes, but few among the higher plants. Ati ‘plants seem to enjoy some decaying organic matter, hence most plants are saprophytes in part where they have an opportunity. Autophyte-- /& plant absolutely independeit. ‘. Parasitism.
Plants which live on living parts of otner plants. Intimate r relations of parasite and host. Rafflesia--no leaves, no stem, hut @ root system, like fungal threads and immense flowers. Found in W. 1 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. gems 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 Yo yercnccccccccce ee eerie 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 Fuss.
5. 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. (c) 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 rutualism. 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 iyvphae of
. " tl Funcsi 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,
@EO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY.
Ithaca, Noe Voy ccc cc neice foe cael 790...
hence are easily blown over. Roots also are contractile as in pulbs. Climbing roots. * 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. Reproduction.
A. Vepetative.
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. In higher plants as Blodea. One individual plant was taken to Europe, 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. Specialized 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 reproductives organs. To prevent self-fertilization, we have 1. 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 Vy cocci Aas pel G Os
7 Meaning 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, hydpthodes 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 tine 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. Llovd thinks that it oes the work of protoszvnthesis. ise ction. A. During Growth Period. B, During Rest Period. C. 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®
Tthaca, No Voy coe . : 5 etait.
5S 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 beosn developed by different conditions? food and nourishmant.
2. Waxy coat or bloom.
Regarded as naving 4 protective function.
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, Ni Yiye ccc 2 osname nsntionti EGO sone
59 .
Many plants seem to have no protection but grow in vositious where they can be away from danger ; 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... Teaf movements. Development of seedlings. Sesadcoats, 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 eicedie 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. Yi, iting Himials
60 Ancient treas,
Lepidodendrons---like Cycopodiums, Calamites---like Equisetiums. Ferns proper. Gymnosperms.
The first two are distinctly xerophytic in structure, hence the question whether the 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
rv?)
advantage of being reafy for work at ali times without beginning again. Power to resist sudden changes as summer frosts.
Sclerophyll or hard-leaved type, as laurel or hollr. Needle-leaved or northern types.
Soft-leaved or southern types.
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---necdle, 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 islend. Am. N.¥. Acad. Science, TL,\Wa\d, 7466
Hollick : dretacaous 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 gigas! 86 valleys have been counted. On the south shore valleys 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--35 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, AN, , Visgscemnaeesenetssichin ss cermin 190...
Historical Geolo:-.
LuArehaeans-Crystalline--found on western part of Long Island--
tie ee Cae 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 Mesozoic 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 gravels,
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. sstpaen 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, best 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 ce oe
Tagzory 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
WUQUS/ bays and pushed up the hills at the sides.
Evidencs 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, NV uy cores csssnnere isin
64 Lecture 1F, August 2, 1900. Phys iographic Ecology 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. deg Topographic form, merely a stage in development of a region. 2, 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.
‘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. YZ ctamreeerse lis rine. = abiuniersentanceeetes 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 because 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. Swch 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 eee to adopt extraordinary methods like the
' Utricularia,
GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY.
Tthaca, No Vij vec i ete creer EGO,
Go
Lecturs 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 coarss. 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. Von priveceedacesenens seston 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 O45). 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 a4 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 Ames 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 hacteris, 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 rere oe
6& drainase. Few bacteria in swamps. Too acid to raise many plants.
Forests--evergreen, tropical forests highest development of plant kingdom. Richer the foges. exaees 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 Permuda.
(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 ; 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 better places.
Another factor is ag guwalonneehas 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 Yay enrccnn sieieereorat
Field Work. Jig 275 L700.
Spit Vegetation.
Drawing.
5,
great quantities.
' Regions 1 and 2 represent the xerophytic side of the beach ;
4, and 5 the hydrophytic area. Under the water wis eel-grass in
owing to the instability of conditions.
gone of annuals since it was covered with water part of the vear.
perennials would be those which had grown
10,
Plants in Region 1. Salsola Kali Saltwort. Chenopodium album Lamb's Quarters.
Cakile Americana Sea-rocket.
-Polygoniun Convolvulus Black Bindweed.
Xanthium Cockle-bur. Atriplex hastata Orache. Ammorphila Sand-reed. Oenothera Primrose.
Strophostyles angulosa
Rhus toxicodendron Poison Ivy.
ll. Solidago sempervirens, Goldenrod.
From the water's edge to high tide was no vegetation
Region 1 might be called the
this vear.
GEO. F. ATKINSON, PROFESSOR OF BOTANY, CORNELL UNIVERSITY.
Ithaca, N. Y.,. 000
12. Bidens frondosa Beggar-ticks. 13. Stromonium (Datina) Stinkweed. 14, Panicum sanguinale |
15, Taraxacum Dandelion.
16. Ambrosia Ragweed.
The most typical forms are Salsola, Cakile, and Number of individuals 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, N. Yu, Sa es te
71 20. Bidens, 21. Chenopodiun, 22. Tactuca Lettuce, 23. llollugo verticillata Carpet-weed. 24, Ailanthus glandulosus. 2f. Rhus, 26. Malva rotundifolia. This zone might be calied the Anmorphila 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
oueda
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 cexian 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 28 os meena serene TQO ai fs
Q
“6
13,
Goodyera pubescens Rattlesnake Plantain
swamp Veretation Fresh Water.
Habenaria tridentats Botrychiun dissecta
Botryciium ternata
Osmunda cinnamonesa
Osmunda resalis
Pteris ayuilina
Woodwardia august ifolia QOuoclea sensibilis Dicksomia punctilobia
Aspidium Thelypteris
Vaccinium corymbosunm Tall swamp bluberry.
Carpinus Water heech,
Betula lenta Sweet birch,
15. 16, hs 18, 19 20, Dl. 22, 25.
24,
Viburnun dentatua
Nyssa sylvatica Sour sum.
Rubrus hispidus mvergreen blackberry. Viola blanda i
Viola prunvfolia
Chryvsosplemim Americanum Golden Saxifraze.
Inpatiens viva Alnus ineana Kalmis latifolia
Elodes campanulata Marsh St. Johnswort.
SL.
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.
Iedeola Virginica.
Tridentalis Americana Chickwesd, Wintergreen.
Vv
itis Labrusca
hhnus venenata
Rhododendron viscosa Azalea (False Honeysuckle).
Northern fox-grape.
Hydrocotyle Americans Water veiuywort.
is
yrola rotundifolia.
Se
Gs
74
Auimist S, 1900.
™)
Ocean Reach at Tire Islxaad.
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 Nake Ilichigan, Several zones may be distinguished.
“ T,. The Ocean Beach Zone. II. First Row of Dunes. III. Inner Dunes, , . Annophila region. ~“?b. 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
recat eat
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 received a cliff-like aspect from tne vigorous wave action. The
direction of the wind being variable the dunes as a whole are not
m
moving, though there is more or less sniftines of the sand. This
sand was purple in some places and was mixed with garnet particles
as well as magnetite.
II, First Dune Recion.
Wathyrus maritimus. Cakile Americana. Oenothera biennis
‘
Solidaso setupervirens. pbuphorbis. polveonifolia.
The inner dunes were the highest on Fire Island, and most nearliz: approxcn moving dunes. They slowed two characteristic zones of vegetation ; first tie Amuophila 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, CUrperus Grayii. III. Plants of the Swamp Regions growing in depressions. 1. Discovleursa capillacea Poneset. Z 2. Evpatiorun perfoliatuns” 3. lycopodium. 4, Sabbatia stellaris 5. Spartima juncea. 6. Potentills anserina. 7, Panicum dichotomun. ' 8. Viola lanceolata. 9. Polygonum acre. Water Stuirtweed. 10. Erechtites hieracifolix Fireweed. 1l. Solidago teimfolia 12. Oenothera fructicosa (var. humifosa).
13. Polt:sola verticelliata.
14, Spiranthes praecox.
70.
#15. Hibiscus Jloschentos Rose-ilallow. 1é,. Pluchea camphorata “Camphor-plant.,
17. KAlmia angustifolia
18s Hide lutun smereeerped 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 tunes and Seach on the Bay Side. Here the flora was essentially like that of the sand spit, xeropnyvtic 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. Betulis populifolis. Populus tremuloides.
iMvrica cerifera. Juniperus Virginiana.
ve
Plants found in hlarsh at Bahb-ion.
Eloides canpanilata Marsh St. Johnswort. :
Habenaria blephaririottis White fringsed-orchid.
ee ae ee
Necture 17, Ausust 8, 1900,
Classification of Plant Societies.
Drude's Handbook of Plant Geography, 1090, purely georray 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 ae as his principal classification, in dividing the world, heat. Torrid, temperates, Arctic, i'’ountain 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. Tne real trouble of Warning's
plan is that he bases ail 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 topographicsl 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. Topograpiuy depends on dvnamics, 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 «ani present. Accumulative effect of environment shown bz: the. ineresse of humus. Each plant society by its own existence prepares tlhe way for its own downfall and its replacement by something else. Hence there mist. he definite suvecession of plants. A sanetic classification such as this is based on relations, Peat bors and -heaths are penetically connected.
Toposrapnic Changes,
Two grest agencies at work in 4 revion, demidation and deposition, affect of such processes, since highest hills most eroded and highest valleys less filled up, is planation. A hill necessarily must he xeropuyvtic and 4 walley hydropnytic ; 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.
72
Stream Veretation August 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 tlie source we found a quantity of Sagina procumbens which always grows best in a cool, shady place.
Sagina procumbens. Lycopus Virginicus. Kupatorum purpureun,
Joe-Pye weed. Eupatorum 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, Galiuia trifidum, vars,
latifolium, Small Bedstraw. 14. Viola blanda. 15, Hloides
canpanulata.
80
Cae
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. Incopus
seminatus. 7. Ludwigia alternifolia, Seed-box,. 8. Mentha viridis,
Spearmint. 9, Mentha piperita, Peppermint. 10. Asplenium Filix- foemina. 11. Hypericum .iudivants, Orange-grass, Pineweed. 12. Houstonia. 13. Polygonum Pennsylvanicun. 14, Vernonia.
Along the wood road grew AnAphalis margaritacea, Pearly ever-
lasting. In the stream was ltricophyllum tenellun.
Lecture 13, August 9, 1900,
I. Progressive Series ue te matrits. 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 swamp 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 wWé nunis.
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 tiie soil gradually
increases as we pass downward.
Hillis (a) Chemical aud Physical Factors. 1. Sand and gravel. (Kames--glacial).
With vracard to the nature of the soil Kames are the same as sand
&2 dines, except the particles are larger, «ud 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. a. Glory Bild is just the opposite, and also erodes more rapidly. On the nills 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 be. 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 and some of the wines,
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 altindé@eis height sahbove the surrounding country. The first has a strong effect and gives rise to distinct zones.
If 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. Tne north slope is xerophytic because there is less heat and an. increased exposure to colder winds, while on the sovth the same condition@ prevail, the soil being drier on account of the greater amount of heat. Rast and west slopes will be mie 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 sbsence of moisture. Hence
the/most portion of + in this case A 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 mesophytic, due to the
increased heat.
on Ke ms
1. If 4 hill is surrouuded vb: other hiils, a mesophytic flora mar 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 Py mesophirtic flors, the other side protecting it just as hills surrounding it may protect .another dat 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 sie in the White Mountains where we have a mesophytic flora hefore a base level is teached. On the otnuer 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 in harbors.
EX. 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 hish tide. Aiternation of submergence and drv land. Hera
we find xerophytic plants forms of Algae.
peach 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.
d. Middle beach from limit of summer to limit of winter storms. Tnis is quiescent in sumer, 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 sand more uniform and finer than beach sand. Heavier elements. not blown up to 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 demiiation and burial, Am.ophila indirectly one of the most commercial plants in the world being a ‘sand-binder. When & dune gets very larg 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, Pru:us
maritanus, Ibrrica cerifera, Rhus toxicendendron.,
Tree Zone follows the shrub. Juniperus Virginiana; then pines and oaks. quercus 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 Sa 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 Crescentic 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.
Lagoons or unirained swamps.
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