Fig. 102. Bulblet-like tubers, such as are occasionally formed on the stem of a Potato-plant above ground.
[111.] The Corm or Solid Bulb, like that of Cyclamen (Fig. [103]), and of Indian Turnip (Fig. [104]), is a very short and thick fleshy subterranean stem, often broader than high. It sends off roots from its lower end, or rather face, leaves and stalks from its upper. The corm of Cyclamen goes on to enlarge and to produce a succession of flowers and leaves year after year. That of Indian Turnip is formed one year and is consumed the next. Fig. [104] represents it in early summer, having below the corm of last year, from which the roots have fallen. It is partly consumed by the growth of the stem for the season, and the corm of the year is forming at base of the stem above the line of roots.
Fig. 103. Corm of Cyclamen, much reduced in size: roots from lower face, leaf-stalks and flower-stalks from the upper.
Fig. 104. Corm of Indian Turnip (Arisæma).
112. The corm of Crocus (Fig. [105, 106]), like that of its relative Gladiolus, is also reproduced annually, the new ones forming upon the summit and sides of the old. Such a corm is like a tuber in budding from the sides, i. e. from the axils of leaves; but these leaves, instead of being small scales, are the sheathing bases of foliage-leaves which covered the surface. It resembles a true bulb in having these sheaths or broad scales; but in the corm or solid bulb, this solid part or stem makes up the principal bulk.
Fig. 105. Corm of a Crocus, the investing sheaths or dead leaf-bases stripped off. The faint cross-lines represent the scars, where the leaves were attached, i. e. the nodes: the spaces between are the internodes. The exhausted corm of the previous year is underneath; forming ones for next year on the summit and sides.