Page:The American Cyclopædia (1879) Volume XIII.djvu/600

 584: PLANT cation of the individual by means of subdi- vision. The strawberry strikes root at each joint of its prostrate stem, a bud is formed there, and at length the stem dies, severing the connection with the old plant, and leaving these rooted portions to shift for themselves as new plants ; the same thing happens with other above-ground stems, some of which only take root at the tip, which bends over and reaches the ground apparently for this very purpose. Propagation by means of under- ground stems or rootstocks is still more com- mon; the rootstocks of the tall blackberry, the passion flower, and others, run along be- low the surface for several feet, and throw up a shoot at the end, which in time becomes an independent plant. As may be seen in some lilies, in dioscorcea, and other plants, buds which have been formed in the axils of the leaves fall to the ground and there take root to form new plants. These methods of multiplication are extensively imitated by the cultivator, and the operations of layering and dividing plants are in imitation of nature's methods ; and we carry it still further in propagating by cut- tings, which is founded upon the fact that the stem, and in many plants even the leaf, will un- der favorable circumstances form adventitious roots ; the majority of plants if treated at the proper time may be multiplied in this way, in many each node being capable of forming a new plant. In grafting and budding the cut- ting, instead of being planted in the soil, is set in the tissues of another but related plant. All such propagation, whether it takes place natu- rally or is done by the aid of man, merely subdivides the individual, and each new plant thus obtained possesses all the peculiarities of the parent. Thus all the potatoes of any given variety, the Early Kose for instance, of which there are untold millions raised each year, are subdivisions of the original plant ; and so the hundreds of thousands of Bartlett pears, all over the world, are in reality parts of the original seedling. That these subdivisions practically retain the peculiarities of the pa- rent plant without variation, except the slight modifications caused by a more or less conge- nial soil, and manifested in size and vigor, is a fact of the highest horticultural importance. Inflorescence. Whatever may be the provision for this kind of multiplication in nature, sooner or later the plant multiplies in another man- ner, by seed. In mentioning the multiplication of the lower orders a plant was cited in which the contents of any two of its cells unite to form a reproductive body or spore. In plants of a higher organization the reproductive body, the seed, is formed by a distinct set of organs, the organs of fructification, and these are col- lectively .the flower. In annual plants the production of flowers often commences when the plant is very young, only a few weeks from the seed, while on the other hand peren- nial plants, especially trees, may go on repeat- ing their organs of vegetation, or growing, for many years; some, like the century plant, which in its native country blooms in 10 or 15 years, spend all their lives in preparing for the event, and when they have bloomed die, as if exhausted with the effort ; while others continue to bloom, if not yearly, at intervals for centuries. Flowers appear either at the end of the stem or in the axils of the leaves, just where leaf buds appear, and like them are either terminal or axillary. Axillary flowers appear at the base of ordinary leaves, usually upon a little stalk or pedicel, but more fre- quently the leaf is reduced in size ; these small- er leaves are termed bracts; if at the same time the internodes of the stem are shortened, one of the commonest forms of flower cluster, the raceme, is produced ; if the flowers are with- out pedicels, or sessile, and crowded, a spike is the result ; and the pedicels of a raceme may be branched and each branch bear a flower, producing a panicle. These forms of inflores- cence are readily seen to be analogous to ordi- nary branching ; others, like the corymb, um- bel, &c., appear to be more complex, but are only modifications of the forms already noted. In a corymb the internodes are short, and the lower pedicels so elongated as to bring their flowers on a plane with the upper ones; in the umbel the internodes are obliterated, the pedicels (rays) all starting apparently at the same point, and of equal length, while the bracts are brought together in a whorl to form an involucre. In the raceme the lower flow- ers are the oldest ; and in many cases the stem or common axis keeps on elongating, so that above new buds are developing while the flow- ers below have fallen, and is said to be inde- terminate, though generally the growth of the stem or axis sooner or later ceases. In the umbel the outer flowers represent the lower ones of the raceme, and are consequently the oldest ; the flowering, beginning at the cir- cumference and proceeding toward the cen- tre, is centripetal, a term applied also to the raceme and similar forms. Where the flower is at the end of the stem, that ceases to elon- gate, and such inflorescence is determinate ; flowers of this kind are often solitary, and when they form a cluster it is by the produc- tion of other flowers upon the stem below the terminal one. In such inflorescence a flat cluster, the cyme, corresponding to a corymb, may be formed, but the oldest flowers will be in the centre ; such inflorescence is centrifu- gal. The term ament or catkin is applied to an elongated cluster of scale-like flowers; a spadix is a fleshy spike upon which the flowers, often imperfect, are closely crowded, as in the Indian turnip, the palms, and others ; this is often protected by a leafy covering, the spathe, which in the Indian turnip, and especially the calla, becomes showy and commonly passes for the flower. There are other forms of inflores- cence which have distinctive names, but they are all traceable to the simple forms here no- ted. Structure of the Mower. The flower has