  A plant is a wonderful organism, yet how few of us realize it as we casually glance at the flowers growing by the wayside. We see a beautiful flower; we know that in the course of time it withers and fades away; and we know that the next year the plant grows up again, sends forth its buds, which at the proper time unfold their petals, and so the cycle continues year after year, while we give little thought to the change that occurs, the cause and its effect. Volumes might be written, and a great many have been since the time of Darwin, upon the many interesting processes by which various flowers are propagated. As this book is confined chiefly to the identification of flowers, we will give but a few illustrations between flowering seasons. We see in most flowers a thing of beauty; their real and, to them, most important function is to produce seeds to perpetuate the species. The parts of a flower that are necessary to produce seeds are the pistil, with its stigma at the top and ovule at the base, and the stamens with their pollen-laden anthers. A flower that has these organs is known as a perfect flower; if, in addition, it has a corolla and calyx, or petals and sepals, it is known as a complete flower. On the opposite page are shown a number of flowers with their parts named. PARTS OF FLOWERS PARTS OF FLOWERS In order that seed may be set, it is necessary that ripened pollen from the anthers should come in contact with the usually sticky stigma, whence it will be transmitted down the style and germinate the ovule. As is well known to be the case with the higher animals, cross-fertilization is necessary in order to insure a good, vigorous species. It is also evident that should the pollen continue to fertilize the ovule in the same flower, the plants in successive generations might become weakened and finally die out and the species be lost. To avoid such a calamity, flowers are constructed so as to facilitate cross-fertilization and the means that some of them adopt towards insuring that end are remarkable. The stamens on most of the simple flowers usually curve outwards, so that the pollen-laden anthers are far enough removed so that there is little danger of the pollen falling on the stigma, at least until after cross-fertilization has already taken place. Others have either the anthers or stigma ripen first, so that it must necessarily be pollen from another blossom that quickens the seed. We all marvel at the industry of the honey bee; how tirelessly it buzzes from flower to flower, from each gathering a drop of the nectar, with which it fills its cells; but we do not always realize the double duty it is doing, for it is a most reliable and active agent for the propagations of a great many plants. Many butterflies, bees, and even beetles unconsciously accomplish the same result, and it is now conceded that each has special colors that are attractive to them. For instance, the bumblebee has a strong preference for blues and purples. The observer will also notice that a bee makes the rounds from flower to flower, taking all of one kind and passing by other species. While this habit undoubtedly avoids some complications, even should he mix his drinks and visit in succession flowers of widely different species, confusion would not be apt to result, for the stigma of one species is usually not responsive to pollen brought from blossoms of another family. Botanists go a step further; not content with the discovery that certain insects like certain colors, they claim (and apparently with good reason) that the bright and showy petals are for the sole purpose of attracting insects; they are, in fact, bill boards advertising the fact that there is a The stigma always partially obstructs the entrance to the food supply, so that the visiting bee must brush against it, and in doing so will leave some of the pollen that he has brought from the last flower visited on its sticky surface. The pollen-dust is attached to the insect in various ways, usually simply by his brushing against the anthers with his hairy body, for it is found that nearly all the useful insects have downy or hairy bodies; other flowers set a sort of spring gun and when the insect steps on the trigger he is showered with the germs (Laurel for example); still others have clefts to catch the legs of visitors, releasing them only if they are strong enough to tear away the pollen masses (such a flower is well illustrated in the Milkweed). Besides having bright colored petals, many of the flowers also have a pleasing odor, this also serving to attract certain kinds of insects; others have very unpleasant odors, like the skunk-cabbage or even like that of putrid meat, as in the carrion flower and the purple trillium, these odors being apparently for the purpose of attracting certain scavenger insects. There are also some flowers, like the evening primrose, that are seen at their best after dusk, when the light-colored petals are widespread and a delicate perfume given off to attract the moths and sphinges that visit them. It is evident that a flower secreting honey may be visited by unwelcome guests, ones that will accept of the nectar, but will make no useful return. Any insect with a shiny, smooth body whether winged or not, is of little use in fertilizing a plant, for even should it receive pollen, it will in all probability have fallen off before the next flower is visited. Ants being particularly fond of sweet things and so small that they can enter a flower without disturbing the anthers, frequently drain the nectar cups so no useful insect will visit them, and they fail to reproduce their kind. The seeds, having been set, are enclosed in a capsule composed of the closed and dried sepals, the petals having fallen off; in a pod as in the peas and beans; or in fruit, as inside an apple, which is formed by the base of the flower enlarging about the seeds with the calyx remaining at the top of the ripened fruit, or in the strawberry, where the seeds are on the outside of the berry and the calyx at the bottom of the fruit. It is plain that should these seeds simply fall to the ground, plants of a single species would soon become so crowded in a small area that the earth could not support them. Consequently various means are furnished different plants for the dispersion of their seeds. A great number, like the thistles, milkweeds and dandelions, have plume-like parachutes provided for each seed, so they can float away on the breeze to new fields; those that have their seeds embedded in fruit are entrusted to birds to be carried where fate wills it; others, like beggar-ticks, burdock, etc., have spines to attach themselves to the clothing of people or to the coats of animals that brush against them. KINDS OF LEAVES KINDS OF LEAVES As certain insects prey upon plants or rob them of their nectar, so certain plants prey upon insects, literally eating them or absorbing them into their system. Best known among these are the pitcher plants, a swamp species, whose leaves are pitcher-like and with a hood or awning over the top to keep out the rain; these leaves are half filled with a sweet fluid that attracts insects, makes them tipsy and causes their death in the watery grave, the plant feeding largely upon the resulting broth. Of another type is the round-leaved sundew, also a common plant; its leaves are covered with short bristly hairs, a drop of gum glistening at the end of each. A fly investigating these is soon caught in the sticky gum and the leaf slowly folds together, enveloping the victim in what might be termed the stomach of the plant. Perhaps the most interesting and surely the most peculiar plant is the Venus fly-trap, which is found only in eastern North Carolina. At the end of each leaf is apparently a smaller one, perhaps an inch in diameter; this is fringed around the edge and rather bristly in the centre. These central bristles are very sensitive and if touched or an insect lights upon the leaf, the two parts of the leaf instantly clasp together on the central stem as a hinge. If nothing is caught, in a short time the trap opens again; if, however, the attempt has been successful it will remain closed for several days or a week, until the victim is entirely absorbed by the glands on the inner surface of the leaf. As in the animal world, so in the plant world; always a struggle for existence, the strong surviving and the weak falling by the wayside. The old adage that “In union there is strength” is amply proved by many of the composite flowers, such as the asters and goldenrods, whose stalks are not only capped with numerous flower-heads, but each flower-head is composed of hundreds of little perfect florets, so closely set together that even should an insect but crawl across the flower-head he will fertilize a number of them. That their plan is a good one is seen by the steady increase in the numbers of these flowers and the rapid strides with which they occupy new territory. On the other hand, compare such flowers as the lady’s slippers, fringed gentian and numbers of others that are yearly becoming less common. |
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