BULB, in botany, a subterranean bud covered with imbricated scales, having at their base a flattened disk, which represents the proper stem of the plant, and from which the roots proceed downwards, whilst from the midst of the scales an annual herbaceous stem and leaves are sent up. The scales are regarded as modified leaves, and sometimes are all fleshy, as in the lily; sometimes the outer ones are membranous, as in the onion, in which case the B. is said to be tunicated. The B. is popularly but erroneously regarded as the root or part of the root of the plant, and plants in which it is found are very generally described as bulbous-rooted. New buds are formed in the axils of its scales, which grow at the expense of the parent B., and gradually destroy it. In some plants, as the tiger-lily and some species of album, leaf-buds (bulbils or bulblets) are developed on the stem above-ground, which spontaneously separate and serve for the propagation of the plant, and which are entirely of the nature of bulbs, being formed of thickened scales, sometimes so closely united as to form a solid mass. The CORM (q.v.) was formerly regarded as a kind of B., and described as a solid B., but its structure is
essentially different, although both it and the TUBER (q.v.) may be included in the description which Linnaeus has given of the B. with reference to the purpose which it serves as "the winter-quarters of the plant." Many bulbs, if removed from the ground i during the period when the vegetation of the plant is most dormant, may be kept in a dry place without injury for a considerable time, even for years. Bulbs serve also for the preservation of plants in periods of drought, and are particularly frequent in those which delight in sandy soils. The abundance of "bulbous-rooted" plants is a remark able characteristic of the flora of the cape of Good Hope. "Bulbous-rooted" plants are very often distinguished by the beauty of their flowers, and many of them are among the most esteemed ornaments of gardens, greenhouses, and stoves. The bulbs of tulips, hyacinths, and other favorite flowers are important articles of trade. Some bulbs, as that of the onion, are valuable as articles of food; others, as that of the squill, from their medicinal properties.