. Lectures on the evolution of plants. Botany; Plants. THE FERNS 123. green tissue enables it to utilize the carbon dioxide of the atmosphere. It is not a long step from such a sporophyte as that of Anthoceros to that of the lower Pteridophytes. In the latter, owing to the early development of a root in the sporophyte, the latter soon becomes quite independent of the gametophyte, which is generally short lived, although occasionally it reaches a considerable size and may live for several years, especially where the sporophyte fails to develop (Fig. 31, A). The sporophyte in even the lowest Pte
. Lectures on the evolution of plants. Botany; Plants. THE FERNS 123. green tissue enables it to utilize the carbon dioxide of the atmosphere. It is not a long step from such a sporophyte as that of Anthoceros to that of the lower Pteridophytes. In the latter, owing to the early development of a root in the sporophyte, the latter soon becomes quite independent of the gametophyte, which is generally short lived, although occasionally it reaches a considerable size and may live for several years, especially where the sporophyte fails to develop (Fig. 31, A). The sporophyte in even the lowest Pterido- phytes exhibits a com- plexity far exceeding that of the highest moss. This is especially. the case in regard to the external differentiation. While in all Bryophytes there is very little development of special external members in the sporophyte, in ferns there are very early developed several characteristic external organs, viz., stem, leaf, and root. The foot, or absorbent organ of the embryo, is much like the corre- sponding organ in the moss-embryo. Corresponding to this development of external mem- FiG. 31.—A, gametophyte of a fern (Marattia), showing a forking of the growing point, and the development of secondary buds, k ; B, gameto- phyte of the same fern, with the young sporophyte J ap, attached; C, a liverwort, Anthoceros, with several sporophytes, sp, attached to the gametophyte, g. The sporophyte is capable of long-continued growth, but does not develop a root, and hence never becomes entirely inde- Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Campbell, Douglas Houghton, 1859-1953. New York, London, The Macmillan company
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