Chapter Viii. Fruits

I. HORTICULTURAL AND BOTANICAL FRUITS

MATERIAL.—Green ears of corn or wheat, fresh pods of beans, young fruits of apple, grape, tomato, melon, buckeye, chestnut, or pecan. A young fruiting stem of squash, gourd, or tomato.

APPLIANCES.—Coloring fluid, glasses of water, a piece of cardboard, tin-foil, vaseline.

EXPERIMENT 87. WHERE DO THE FOOD SUBSTANCES CONTAINED IN FRUITS COME FROM?—Apply your food tests to the pulp of a young apple, squash, bean pod, chestnut, buckeye, or a “green” ear of corn or wheat, and see what it contains. Test the stem and roots of a plant of the same kind in the same way. Do you find the same foods in them? Where is the food stored?

EXPERIMENT 88. THROUGH WHAT PARTS OF THE STEM AND FRUIT DO WATER AND NOURISHMENT TRAVEL TO THE SEED?—Cut a young squash or cucumber from the vine, leaving stem enough to insert by its cut end in a glass of eosin solution. Leave for two or three days, then make a vertical section through the stem and fruit. What course has the liquid followed? Can you trace some of it into each seed? Do you see now a use for the seed stalk and the rhaphe?

EXPERIMENT 89. DOES THE SURFACE OF FRUITS GIVE OFF WATER BY TRANSPIRATION?—Try Exp. 59, using in place of leaves a young squash, eggplant, or a bunch of grapes, and after a day or two notice whether any moisture has been given off. If the fruit skin gives off moisture, it is natural to expect that it would be provided with stomata, like other transpiring organs. To find out whether this is so, place a thin piece of the outer epidermis of a grape, tomato, plum, or apple under the microscope. Do you find stomata on any of them? Do you see anything else? Try the skin of an apple, and compare the corky dots you find there with those on the bark of a young dicotyl stem (118) and decide what they are.

EXPERIMENT 90. WILL FRUITS RIPEN WELL IN THE ABSENCE OF LIGHT AND AIR?—Envelop a number of immature fruits in bags of dark cloth or paper so that no light can reach them. Keep a number of others well coated with oil or vaseline, and watch. Do the fruits so treated mature as quickly or develop as fully as those of the same kind left untreated?

EXPERIMENT 91. WHAT IS THE USE OF THE RIND TO THE FRUIT?—Select two apples of equal size, peel one, and weigh both. After 12 to 24 hours, weigh them again. Which shows the greater loss in weight? Leave peeled and unpeeled fruits in an exposed place and see which is the more readily attacked by insects. Which decays the sooner? What are some of the uses of the rind?

=282. What is a fruit?=—Horticulturally and commercially the distinction between a fruit and a vegetable depends very much upon the use we make of it—whether as food, or as a mere gratification of the palate. Broadly speaking, those fruits that are lacking in sugar, as the tomato and cucumber, are classed as vegetables. Botanically, a fruit is any ripened seed vessel, or ovary, with such connected parts as may have become incorporated with it; and hence, to the botanist, a boll of cotton, a tickseed, or a cocklebur is just as much a fruit as a peach or a watermelon.

=283. Classification of fruits.=—For convenience of description, fruits are classed as:

(a) Dry or fleshy, according as they have a more or less hard and bony, or soft and fleshy, texture.

(b) Dehiscent, or indehiscent, according as they open at maturity in a regular way to discharge their seed, or remain closed until the covering wears away or is burst by the germinating embryo.

Fleshy fruits are very seldom dehiscent, though some few, as the balsam apple and the chayote, or one-seeded squash, discharge their seed when mature. The banana and some other fleshy fruits, when peeled, separate along regular lines, and in this respect behave very much as if they were fleshy pods.

=284. When is a fruit ripe?=—A fruit is ripe horticulturally, when it is good to eat; it is ripe botanically, when it has set its seed. Many of our choicest table fruits, such as the pineapple, banana, and most varieties of fig, seldom are botanically ripe, since they rarely produce perfect seeds.

It is the constant effort of the horticulturist to develop those parts of a plant that are useful to man, while in a state of nature the plant seeks to develop such parts as best serve its own purpose in the struggle for existence. The plants most useful to man have, as a general thing, been subjected to a long course of artificial breeding and selection. They are forced developments, often monstrosities, from the plant’s point of view, if we could conceive of it as capable of having an opinion. Nature is continually striving to reclaim them; and if left to themselves, they must either obey “the call of the wild,” or die out.

=285. Seedless fruits and vegetables.=—As the seed is the most important thing to the plant, the edible parts in wild fruits are, as a rule, subsidiary to its development. In a state of nature, fruits will generally wither and drop from the stem, if for any reason they have become incapable of perfecting their seed. It is only in a few kinds, limited to those which can successfully propagate themselves by other means, that the production of seed does not take place. Among cultivated species, however, where propagation is carefully provided for by man, the seed is of less importance, and sterile varieties that might soon die out under natural conditions, continue their existence indefinitely under his fostering hand. The seeds of edible fruits are, as a general thing, both indigestible and unpalatable (21), and hence the efforts of the horticulturist are directed largely to getting rid of them, or to very greatly reducing their size and number in proportion to the edible parts.

=286. How seedless fruits arise.=—The perfecting of seed requires a great consumption of food and energy on the part of the plant, and when it is led, for any reason, to expend an unusual amount of force in some other function,—as for instance, in producing tubers or in growing bulbs,—it is apt to bear few seeds and to depend more or less completely upon other methods of reproduction.

Among cultivated plants, selection on the part of man, whether conscious or unconscious, has perhaps contributed more than any other cause to bring about the same result. To this agency is probably due the development of our common domestic fig, of which over four hundred varieties that mature fruits without fertilization are cultivated in the United States alone. The fig was one of the earliest fruits known to cultivation; and the early navigators, ignorant of the processes of fertilization, would naturally, in choosing specimens to carry home with them, select only fruit-bearing trees. Such of these as matured fruits would be preserved and propagated, until, by repeated selection, hundreds of edible varieties have been developed that ripen fruits without caprification (279).

=287. The use of the fruit to the plant.=—The object of the fruit is to furnish protection to the seeds during their period of development and inactivity, and to aid in various ways the work of dispersal. It probably takes part also in digesting and diffusing nourishment for the use of the developing seeds. It has been shown in previous chapters that plants, almost without exception, are in the habit of storing up food in various ways as a provision for fruiting. That a large portion of the stored nourishment is used up in the performance of this function is proved by its disappearance from those parts—for example, from fleshy roots, such as beets and turnips, after they have “gone to seed.”

Practical Questions

1. What is the use of the down on the peach? The bloom of the plum and grape? [202, (1); Exp. 91.]

2. Why are apples, pears, plums, and other fleshy fruits nearly always rosier on one side than on the other? (Exp. 90.)

3. Can annuals be improved in any other way than by seed selection?

4. Would a seedless annual be perpetuated under natural conditions?

5. Why is decrease of moisture and increase of light desirable as the fruiting season approaches? (126, 127; Exp. 90.)

6. Why are turnips, carrots, and other fleshy roots unfit to eat if left over till the plants have seeded? (92, 287.)

II. FLESHY FRUITS

MATERIAL.—A specimen of each of the four principal kinds of fleshy fruits. Examples of the pome are: apple, pear, quince, rose hip, haw; of the berry: grape, tomato, cranberry, currant, gooseberry, lemon; of the pepo: melon, squash, pumpkin; of the drupe: peach, plum, cherry, dogwood. Specimens of the commoner kinds can nearly always be found in the market; if nothing better is available, pickled and dried ones may be used—figs, prunes, dates, raisins, etc.

=288. Dissection of a pome fruit.=—Examine with a lens the outside of an apple or a pear. Can you make out the lenticels? What difference in color do you notice between the ripe and unripe fruit? What difference in taste? What substance would you judge from this, do ripe fruits contain which green ones do not? Test both kinds for sugar and starch; which contains the more of each? Strictly speaking, sugar and starch are merely different forms of the same chemical compound. In ripe fruits the starch has been cooked by the sun and converted into sugar.

With the point of a pencil separate the little dry scales that cover the depression in the center of the fruit at the end opposite the stem. How many of them are there? How does this accord with the plan of the flower as outlined in 229? They are the remains of the sepals, as will be more apparent on comparing them with the larger and more leaflike ones on a hip, which is clearly only the end of the footstalk enlarged and hollowed out with the calyx sepals at the top. Cut a cross section midway between the stem and the blossom end, and make an enlarged sketch of it. Label the thin, papery walls that inclose the seed, carpels. How many of them are there, and how many seeds does each contain? The carpels, together with all that portion of the fruit which surrounds and adheres to the ovary, constitute the pericarp, or wall of the seed vessel. The fleshy part of the apple is no part of the ovary proper, but consists merely of the receptacle, or end of the footstalk, which becomes greatly enlarged and thickened in fruit. Look for a ring of dots outside the carpels, connected (usually) by a faint scalloped line. How many of these dots are there? How do they compare in number with the carpels? With the remnants of the sepals adhering to the blossom end of the fruit?

Next make a vertical section through a fruit, and sketch, enlarging it sufficiently to show all the parts distinctly. Observe the line of woody fibers outside the carpels, inclosing the core of the apple. Compare this with your cross section; to what does it correspond? Where do these threads originate? Where do they end? Can you make out what they are? (176.) Notice how and where the stem is attached to the fruit. Label the external portion of the stem, peduncle; the upper part, from which the fibrovascular bundles branch, the receptacle. It is the enlargement of this which forms the fleshy part of the fruit. Try to find out, with the aid of your lens and dissecting pins, the exact spot at which the seeds are attached to the carpels, and label this point, placenta. Notice whether it is in the axis where the carpels all meet at their inner edges, or on the outer side. Observe, also, whether the seed is attached to the placenta by its big or its little end. If you can find a tiny thread that attaches the seed to the carpel; label it, seed stalk. Fruits of this kind are classed, botanically, as pomes. Write, from your analysis, a definition of the pome.

=289. Modifications of the receptacle.=—Compare with the drawings you have made, a haw and a hip. What points of agreement do you see? What differences? Which of the two more closely resembles the typical pome? The receptacle is subject to a variety of modifications, and forms a part of many fruits, for example, the fig, lotus, and calycanthus (Figs. 370, 371); but a fruit is not a pome unless the containing receptacle becomes more or less soft and edible.

=290. The pepo, or melon.=—Next examine a gourd, cucumber, squash, or any kind of melon, and compare its blossom end with that of the apple or pear. Do you find any remains of a calyx, or other part of the flower? Examine the peduncle and observe how the fruit is attached to it. Can you tell what made the outer epidermis of the rind? Put a small piece under the microscope; do you see any stomata, or lenticels? Cut cross and vertical sections, and sketch them, labeling each part. There may be some difficulty in making out the carpels, for they are not separate and distinct as in the pome, but confluent with the enlarged receptacle, which in these fruits forms the outer portion of the rind, and also with each other at their edges, so as to form one unbroken circle, as if they had all grown together. And this is precisely what has happened. The placentas are greatly enlarged and modified, and it may be necessary to refer to the diagram, Fig. 372, c, in order to make them out. How many locules, or chambers, are there in your specimen? How many placentas? Notice that these are central and double, but extend to the pericarp before dividing so that they appear to be parietal, and twice their real number, which is only three. Are the seeds vertical, as in the apple, or horizontal? Look for the little stalk, or thread, that attaches them to the placenta.

Pepo is the name given by botanists to this kind of fruit. Write in your notebook a proper definition of it, from the specimens examined.

=291. The berry.=—Examine a tomato, an eggplant, a grape, cranberry, lemon, or orange, in both cross and vertical section, and compare it with the melon and the apple. What differences and resemblances do you find? Cut a cross section, and draw, showing the attachment of the seeds. How many locules are there? Normally the tomato is a two-celled fruit, like the potato berry (Fig. 374), but it has been so modified by cultivation that the original plan is not always easy to distinguish. See if you can make it out. Do the seeds in your specimen appear to be healthy and well developed, or are some of them small and aborted? How do you account for this? (285, 286.) What difference do you notice in color between the ripe and unripe fruit? Write a definition of the berry from the study you have made of it.

Berries are the commonest of all fleshy fruits, and the most variable and difficult to define. In general, any soft, pulpy, or juicy mass, like the grape and tomato, whether one or many seeded, inclosed in a containing envelope, whether skin or rind, is a berry. Its typical forms are such fruits as the grape, mistletoe, pokeberry, etc., though such diverse forms as the eggplant, persimmon, red pepper, orange, banana, and pomegranate have been classed as berries; and, in fact, the melon and the pumpkin are only greatly modified kinds of the same fruit. In popular language, any small, round, edible fruit is called a berry. This is a good commercial classification, though not botanically correct.

=292. The drupe, or stone fruit.=—Examine a section of a green plum, peach, or cherry, before the stone has hardened, and tell from what part it is formed. This stony covering, composed of the inner layer of the pericarp, and enveloping the seed like an outer coat, is the main distinction between the drupe and the berry, but it is not always possible to make out its real nature except by an examination of the young ovary. In a green drupe, before the stone has hardened, its connection with the fleshy part is very evident, and the ripe fruit will answer inquiries if we know how to put them. Open the stone, and the seed will be exposed with its own coverings inside. When a stone has more than one kernel,—for instance, an almond or peach stone, —the stone is not a seed coat, but the hardened inner wall of a seed vessel or ovary; for a seed coat can never contain more than one seed, any more than the same skin can contain more than one animal.

All the fruits considered in this section belong to the fleshy class. These form the bulk of the fruits sold in the market, and are of special importance to the horticulturist.

Practical Questions

1. Is the tomato horticulturally a fruit or a vegetable? the squash? eggplant? cranberry? olive? elderberry? pepper? date? maypop? crab apple? black haw? To what class does each belong? (283, 288-292.)

2. Of what use to the plant is the hard stone of the drupe? (21.)

3. Is the pulp of fleshy fruits agreeable to the taste before they are ripe? After? What advantage is this to the plant? (21.)

4. Are the seeds of edible fruits, as a general thing, digestible or agreeable to the palate?

5. Is this an advantage to man? To the plant? (21, 284, 285.)

6. What are the most common fleshy fruits in autumn?

7. With what vegetative parts of the plant does the skin of many fruits present correspondences? Are these such as to indicate homology, or analogy only, between them? (100, 118, 288, 289; Exp. 89.)

8. Name six of the most watery fruits that grow in your neighborhood.

9. Under what conditions as to soil, heat, moisture, etc., does each thrive best?

10. Would a gardener act wisely to infer that because a fruit contains a great deal of water it should be planted in a very wet place?

11. Which contains more water, the fruit or the leaves of the apple?

12. Why does not the fruit, when separated from the tree, wither as quickly as do the leaves? (Exp. 91.)

III. DRY FRUITS

MATERIAL.—Some easily attainable specimens of dry fruits are (1) nuts: acorn, hickory nut, walnut, chestnut, pecan, filbert; (2) pods: pea and bean pods, capsules of larkspur, milkweed, jimson weed, cotton; (3) grains: corn, wheat, oats, rice; (4) akene: sunflower, thistle, dandelion, buckwheat, clematis.

=293. Importance of dry fruits.=—Dry fruits are not in general so conspicuous or so attractive as fleshy ones, but on account of their great number and variety they offer a wide field for study. They are also of great interest from an economic point of view: (1) because they include the cereal grains that furnish so large a portion of our food, and (2) because the greater part of the troublesome weeds that infest our crops are scattered by fruits of this class.

=294. Indehiscent fruits.=—These kinds are so simple that it will not be necessary to give much time to them. Compare an acorn, a chestnut, or a filbert with a ripe bean pod or with a capsule of morning-glory. Try to open each with your fingers; which dehisces, or opens, the more readily? Which is indehiscent, having no regular way of opening? How many seeds or kernels do you find in the dehiscent pod? How many in the indehiscent one? Would it be of any advantage for a one-seeded pod to open? Remove the kernel from the indehiscent fruit; has it any covering besides the shell? Which is the pericarp, and which the seed coat?

=295. The nut= is easily recognized by its hard, bony covering, containing usually, when mature, a single large seed that fills the interior. Care should be taken not to confound with true nuts, large bony seeds, like those of the buckeye, horse-chestnut, date, and the Brazil nut sold in the markets. In the true nut, the hard covering is the seed vessel, or pericarp, and not a part of the seed itself, though it often adheres to it so closely as to seem so. In bony seeds, like those of the horse-chestnut and persimmon, the hard covering is the outer seed coat. The distinction is not always easy to make out unless the seed can be examined while still attached to the placenta of the fruit.

=296. The akene=, of which we have examples in the tailed fruit of the clematis, the tiny pits on the strawberry, and the so-called seeds of the thistle, dandelion, and sunflower, is a small, dry, one-seeded, indehiscent fruit, so like a naked seed that it is generally taken for one by persons not acquainted with botany. It is the commonest of all fruits, and there are so many kinds that special names have been applied to some of the most marked varieties. The akene of the composite family may generally be known by the various appendages in the form of scales, hooks, hairs, or chaff, that crown it (Figs. 309-314). The fruits of the parsley family are merely a sort of double akene attached by the inner face to a slender stalk from which it separates at maturity.

The samara, or key fruit, is an akene provided with a wing to aid in its dispersion by the wind. The maple, ash, and elm furnish familiar examples.

=297. The grain=, so familiar to us in all kinds of grasses, is economically the most important of all fruits. It is popularly classed as a seed, and for practical purposes may be treated as such, but it is really a modification of the akene in which the seed coats have so completely fused with the pericarp that they can no longer be distinguished as separate organs. Peel the husk from a grain of corn that has been soaked for twenty-four hours, and you will find the contents exposed without any covering; remove the shell of an acorn or a hickory nut, and the seed will still be enveloped by its own coats. Would it be of any advantage for the seed of an indehiscent fruit, like a grain of corn or oats, to have a separate special covering of its own?

=298. Dehiscent fruits.=—Pod, or capsule, is the general name applied to all dehiscent fruits. The simplest possible kind of pod is the follicle, composed of a single carpel, like those of the larkspur, milkweed, and marsh marigold, and may be regarded as a modified leaf. Examine one of these pods and you will find that it splits down one side, which corresponds to the edges of the leaf brought together and turned inward to form a placenta for the attachment of the seed. This line of union is called a “suture,” from a Latin word meaning a “seam.”

=299. The legume.=—Get a pod of any kind of bean or pea, and observe that it differs from the follicle in having two sutures or lines of dehiscence. One of these runs along the back of the carpel and corresponds to the midrib of the leaf; the other, corresponding to the united edges of the carpellary leaf, always turns inward, toward the axis of the flower, and forms the placenta.

The beggar-ticks, so unpleasantly familiar to most of us, are merely a kind of legume constricted between the seeds and breaking up into separate joints at maturity. What kind of indehiscent fruits do the joints become when separated? (296.)

=300. Compound or syncarpous pods.=—The carpellary leaves may unite either by their open edges, as if a whorl like that represented in Fig. 188 were to grow together by the margins (Fig. 395); or each may first roll itself into a simple follicle like the larkspur and columbine (Fig. 396), and then a number of these may unite by their ventral sutures into a single syncarpous capsule, with as many locules as there are carpels (Fig. 398). The seed-bearing sutures being all brought together in the center, the placenta becomes central and axial. In the first case (Fig. 395) the open carpels form a one-chambered capsule, though the placentas sometimes project, as in the cotton, so far as to produce the effect of true partitions with a central axial placenta. In capsules with only one compartment, the number of carpels can generally be determined by the number of sutures or of placentas.

Practical Questions

1. To what class of fruits does each of the following belong—rice; beggar-ticks; poppy; peanut; jimson weed; chinquapin; caraway?

2. Is the coconut, as usually sold in the market, a fruit or a seed?

Suggestion: carefully examine the “eyes,” from without and from within; if you can get a specimen with the husk on, it will help to a decision.

3. Can you name any syncarpous, or compound capsule, that is single-seeded?

4. Can you name any indehiscent fruit that has normally more than one seed?

5. Give a reason for the difference. (23.)

6. Name the weeds of your neighborhood that are most troublesome on account of their adhesive fruits.

7. Do these fruits belong, as a rule, to the dehiscent or to the indehiscent class?

8. Give a reason for the difference, if any is noted. (23.)

IV. ACCESSORY, AGGREGATE, AND MULTIPLE FRUITS

MATERIAL.—For autumn and winter, examples of accessory fruits are: pineapple, common apple, pear, rose hip; aggregate: magnolia, tulip tree, wild cucumber, sweet flag (Calamus); multiple: osage orange, sweet gum balls, pine cones, figs, fresh or dried.

For spring and summer, examples of accessory fruits are: raspberry, strawberry, squash, cucumber; aggregate: strawberry, blackberry, Jack-in-the-pulpit; multiple: fig, mulberry. Most of those named will be found to belong to more than one class; the strawberry, for instance, is both accessory and aggregate; the fig and pineapple, accessory and multiple.

=301.= Besides the varieties already named, all fruits, whether fleshy or dry, may be simple, accessory, aggregate, or collective. Fruits of the first kind need no explanation; they consist merely of a single ripened ovary, whether of one or more carpels, as the peach, cherry, bean, and lemon.

=302. Accessory fruits= are so called because some other part than the seed vessel, or ovary proper, is coherent with, or accessory to it, in forming the fruit, as in the apple and the hip. The accessory part may consist of any organ, but is more frequently the calyx or the receptacle. In the strawberry, the little hard bodies, usually called seeds, that dot the surface are the true fruits (akenes). A vertical section through the center will show the edible part to consist wholly of the enlarged receptacle. In the pineapple, the edible stalk may be traced through a mass of flowers whose seed vessels have become enlarged and ripened into fruits.

=303. Aggregate fruits.=—Some accessory fruits, the strawberry and blackberry for example, are, at the same time, aggregate; that is, they are composed of a number of separate individual fruits produced from a single flower. The cone of the magnolia and of the tulip tree are aggregate fruits; can you name any others?

=304. Collective, or multiple, fruits.=—The pineapple is an example of both an accessory and a multiple fruit, being composed of the ripened ovaries of a number of separate flowers that have become more or less coherent. The osage orange, sweet gum balls, fig, and mulberry are other examples of this class.

=305. Dissection of a multiple fruit.=—Get one of the dried figs sold by the grocers. Look at the small end where the skin originates; of what part is it a modification? (289.) Can think of a reason for this curious, urnlike enlargement of the receptacle? Is there anything about the fig, for instance, that renders it peculiarly liable to be preyed upon by birds and insects? Could any but a very small insect get through the eye without injuring the fruit? Could it free itself from the sticky mass inside and get out again without difficulty? Would you judge from this that the caprification of the fig is easily effected (279), even when the fig wasp is present? Can you now account for the fact that over four hundred varieties of cultivated figs ripen their fruit without fertilization?

Open your specimen and examine the contents; what do you find? From a dried specimen it will hardly be practicable to make out clearly that the pulp of the fig consists of hundreds of tiny pistillate blossoms that line the inner face of the receptacle. The little grains usually taken for seeds are really small akenes—the ripened ovaries of flowers that have been pollinated from the caprifig (279, 286). Crush one gently and examine with a lens, or under a low power of the microscope. It is these “botanically” ripe fruits (284) that give to the dried figs of commerce their plumpness and their pleasant, nutty flavor. Why are our native American figs lacking in these qualities (279)? Could this defect be remedied? Do you know of any efforts being made in that direction by American cultivators?

=306. Fruit clusters.=—Be careful not to confound aggregate and collective fruits with mere clusters, like a bunch of grapes or of sumac berries. The distinction is not always easy to make out. The clump of akenes that make up a dandelion ball, for instance, though held on a common receptacle, like the mulberry and other collective fruits, have so little connection with each other, and separate so completely at maturity, as to partake more of the nature of a cluster than of a collective fruit. The same is true of the clump of tailed akenes that make up the fruit of the clematis. Though the product of a single flower and thus technically an aggregate fruit, they are really only a compact head or cluster. Some degree of cohesion is necessary to constitute a cluster of matured ovaries into an aggregate or a multiple fruit.

=307. The individual fruits= that make up the various kinds just described may belong to any of the classes mentioned in the two preceding sections: those of the blackberry, for instance, are drupes; of the strawberry, akenes; of the sweet gum, capsules.

Practical Questions

1. To what class of fruits would you refer the following: a banana; a tickseed; a dewberry; a cocklebur; a string bean; a watermelon; a cantaloupe; a pomegranate; a black haw; a dogwood berry; a red pepper?

2. Tell which of the following are aggregate or multiple fruits, and which are fruit clusters: an ear of corn; of wheat; a buttonwood or a sycamore ball; a hop; a dewberry; a pine cone; a prickly pear. (303, 304, 306.)

3. Tell the nature of the individual fruits composing the different combinations mentioned in the last question.

4. Can you suggest any advantage that might accrue to a species from having its fruits clustered or compound? (21, 23, 24, 287.)

Field Work

1. Study the various edible fruits of your neighborhood with regard to their means of dissemination and protection. Consider the object of the protective adaptations in each case, whether against heat, cold, moisture, animals, etc. Notice the color of the different kinds, and trace its significance; for example, the bright red of the holly, the dull color of muscadine, black haw, and wild smilax. Account for the prevalence of red among autumn fruits. Notice the position of the fruit on the bough and explain its object; as, for instance, the clustering of dogwood at the end of the twig, the pendent position of grapes and honey locusts. Observe the relation between the color and size of fruits and their grouping. What advantage is it for sumac and bird haws to be gathered in large clusters?

2. Compare wild with cultivated fruits and notice in what respects man has altered the latter for his own benefit. Note, for instance, the difference between cultivated apples and the wild crab, between the cultivated grains and wild grasses. Observe the great number of varieties of each kind in cultivation and try to account for it.

3. Notice the situations in which different kinds of fruits grow, whether hot, dry, moist, windy, or sheltered, and how they are affected by their surroundings. For example, account for the difference between blackberries growing on a dry hillside, and those in moist land along the borders of a stream. Give the conclusions drawn from your observations in each case.

4. Notice what animals feed upon the different kinds, and whether their visits are harmful or beneficial. Consider in what respects the interests of the plant itself, the interests of man, and the interests of other animals may clash or coincide. Examine the vegetation along the hedgerows and borders of fields and old fences. Notice the kind of plants that compose it—sumac, sassafras, cedars, cat brier, etc. The list will be slightly different for different localities, but this will not alter the general conclusion. What kinds of fruits and seeds do these shrubs produce? What kinds of living creatures frequent hedgerows and feed upon the seeds of such plants? Do you see any relation between these facts and one of the modes of seed dispersal?

5. Classify all the fruits you have collected during your walk, under their proper heads, as fleshy or dry, dehiscent or indehiscent, simple, accessory, aggregate, collective. Be careful to distinguish between compact clusters, like the heads of clematis or buttonwood, and truly compound fruits.