Page:Elementary Botany.pdf/13

 * Germination of Maize.—In germination the contents of the seed swell, the radicle bursts through the base of the cotyledon and the outer covering of the seed, and grows downwards (fig. 4, 1). Other roots are also produced from the base of the plumule, breaking through the base of the scutellum; these are called adventitious roots (fig. 4, 2, 8. ). The plumule curves upwards, consisting of leaves which sheathe the stem. The lower part of the cotyledon remains inside the seed, absorbing the endosperm, and passing it on to the growing radicle and plumule, but the upper part elongates slightly and sheathes the base of the plumule. The bottom of the cotyledon, ruptured by the radicle, is called the root sheath.

Mustard or Cress.—The seed (figs. 5-9) consists of:—
 * (1) an outer covering, the testa, enclosing—


 * (2) the embryo. The embryo consists of:—


 * (a) the radicle,


 * (b) the plumule,