. A Manual of botany : being an introduction to the study of the structure, physiology, and classification of plants . Botany. Fig. 626. radicles, r and /, pierce the iategument at the base, and are each covered with a separate sheath, m, called coleorhiza (fig. 105, p. 42). In aperispermic Monocotyledons, as Alismacese and Potamese (fig. 595, p. 334), the cotyledon does not remain within the seed, but is raised above the ground, c, giving origin to the plumule, g, which is at first enclosed in its sheath. Thus the cotyledon follows the development of i^eaves. Its limb is first produced, and i
. A Manual of botany : being an introduction to the study of the structure, physiology, and classification of plants . Botany. Fig. 626. radicles, r and /, pierce the iategument at the base, and are each covered with a separate sheath, m, called coleorhiza (fig. 105, p. 42). In aperispermic Monocotyledons, as Alismacese and Potamese (fig. 595, p. 334), the cotyledon does not remain within the seed, but is raised above the ground, c, giving origin to the plumule, g, which is at first enclosed in its sheath. Thus the cotyledon follows the development of i^eaves. Its limb is first produced, and is either pushed above ground, or is confined within the seed. In the latter case it is arrested iu its progress; subsequently, a sheath is formed which may either be a direct continuation of the limb, or may be separated from it by a petiolary portion. When the limb is confined in the seed, and ceases to be developed, the sheath often continues to grow, forming a marked covering of the axis. The rootlets in Monocotyledons during germination (fig. 105 r r, p. 42) pierce the radicular extremity of the embryo, and become covered with sheaths or coleorhizas, c c, formed by a superficial layer of cellular tissue. As the radicular extremity Pig. 626. Germination of tlie monocotyledonous perispermic seed of Canna indica. The seed is cnt to show the relation hetween the perisperm and the embryo at different stages, the former diminishing, while the, latter increases, e. Envelope or spermoderm. o, Its upper part, which is separated like a lid or operculum, to allow the passage of the radicle. J), Perisperm or albumen, c. Cotyledon, r, Eadicle or young root. / /, Secondary radicles, w, Coleorhiza or sheath of the roots. /, Slit indicating the position of the gem- mule ; at this slit an elongated sheath, v, is protruded, o o. Narrow portion of the cotyle- don (corresponding to the petiolary portion), intermediate between its enlarged portion, t (corresponding to the lamina or limb of the
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1875
