Until a comparatively recent period the interest in plants centred largely in the medicinal properties, and sometimes in the supernatural powers, which were attributed to them.
- O who can tell The hidden power of herbes and might of magick spell ? sang Spenser in the "Faerie Queene; " and to this day the names of many of our wayside plants bear witness, not alone to the healing properties which their owners were supposed to possess, but also to the firm hold which the so-called " doctrine of signatures" had upon the superstitious mind of the public. In an early work on "The Art of Simpling," by one William Coles, we read as follows: "Yet the mercy of God which is over all his works, maketh Grasse to grow upon the Mountains and Herbes for the use of men, and hath not only stamped upon them a distinct forme, but also given them particular signatures, whereby a man may read, even in legible characters, the use of them." Our hepatica or liver-leaf, owes both its generic and English titles to its leaves, which suggested the form of the organ after which the plant is named, and caused it to be considered "a sovereign remedy against the heat and inflammation of the liver." *
Although his once-renowned system of classification has since been discarded on account of its artificial character, it is probably to Linnaeus that the honor is due of having raised the study of plants to a rank which had never before been accorded it. The Swedish naturalist contrived to inspire his disciples with an enthusiasm and to invest the flowers with a charm and personality which awakened a wide-spread interest in the subject. It is only since his day that the unscientific nature-lover, wandering through those woods and fields where wide around, the marriage of the plants Is sweetly solemnized has marvelled to find the same laws in vogue in the floral as in the animal world.
To Darwin we owe our knowledge of the significance of color, form, and fragrance in flowers. These subjects have been widely discussed during the last twenty-five years, because of their close connection with the theory of natural selection; they have also been more or less enlarged upon in modern text-books. Nevertheless, it seems wiser to repeat what is perhaps already known to the reader, and to allude to some of the interesting theories connected with these topics, rather than to incur the risk of obscurity by omitting all explanation of facts and deductions to which it is frequently necessary to refer.
It is agreed that the object of a flower's life is the making of seed, i.e., the continuance of its kind. Consequently its most essential parts are its reproductive organs, the stamens, and the pistil or pistils.
The stamens (p. II) are the fertilizing organs. These produce the powdery, quickening material called pollen, in little sacs which are borne at the tips of their slender stalks.
The pistil (p. II) is the seed-bearing organ. The pollen-grains which are deposited on its roughened summit throw out minute tubes which reach the little ovules in the ovary below and quicken them into life.
These two kinds of organs can easily be distinguished in any large, simple, complete flower (p. 10). The pollen of the stamens, and the ovules which line the base of the pistil, can also be detected with the aid of an ordinary magnifying glass.
Now, we have been shown that nature apparently prefers that the pistil of a flower should not receive its pollen from the stamens in the same flower-cup with itself. Experience teaches that, sometimes, when this happens no seeds result. At other times the seeds appear, but they are less healthy and vigorous than those which are the outcome of cross-fertilization - the term used by botanists to describe the quickening of the ovules in one blossom by the pollen from another.
But perhaps we hardly realize the importance of abundant health and vigor in a plant's offspring.
Let us suppose that our eyes are so keen as to enable us to note the different seeds which, during one summer, seek to secure a foothold in some few square inches of the sheltered roadside. The neighboring herb Roberts and jewel-weeds discharge - catapult fashion - several small invaders into the very heart of the little territory. A battalion of silky-tufted seeds from the cracked pods of the milkweed float downward and take lazy possession of the soil, while the heavy rains wash into their immediate vicinity those of the violet from the overhanging bank. The hooked fruit of the stick-tight is finally brushed from the hair of some exasperated animal by the jagged branches of the neighboring thicket and is deposited on the disputed ground, while a bird passing just overhead drops earthward the seed of the partridge berry. The ammunition of the witch-hazel, too, is shot into the midst of this growing colony; to say nothing of a myriad more little squatters that are wafted or washed or dropped or flung upon this one bit of earth, which is thus transformed into a bloodless battle-ground, and which is incapable of yielding nourishment to one-half or one-tenth or even one hundredth of these tiny strugglers for life !
So, to avoid diminishing the vigor of their progeny by self-fertilization (the reverse of cross-fertilization), various species take various precautions. In one species the pistil is so placed that the pollen of the neighboring stamens cannot reach it. In others one of these two organs ripens before the other, with the result that the contact of the pollen with the stigma of the pistil would be ineffectual. Often the stamens and pistils are in different flowers, sometimes on different plants. But these pistils must, if possible, receive the necessary pollen in some way and fulfil their destiny by setting seed. And we have been shown that frequently it is brought to them by insects, occasionally by birds, and that sometimes it is blown to them by the winds.