Nature and development of plants . Fig. 230. Germination of the gametospore: A, section of archegoniumafter fertilization, showing the four-celled stage of the germinating gameto-spore. The cell r by repeated division forms the first root, c forms thefirst leaf, s forms the stem and f the foot; x. apical cell of , later stage. The young sporophyte rupturing the archegonium orcalyptra, lettering as in A. an independent and self-supporting plant. The first leaf is smalland usually bears little resemblance to those of the mature plant,. Fig. 231. Older sporophyte that lias developed
Nature and development of plants . Fig. 230. Germination of the gametospore: A, section of archegoniumafter fertilization, showing the four-celled stage of the germinating gameto-spore. The cell r by repeated division forms the first root, c forms thefirst leaf, s forms the stem and f the foot; x. apical cell of , later stage. The young sporophyte rupturing the archegonium orcalyptra, lettering as in A. an independent and self-supporting plant. The first leaf is smalland usually bears little resemblance to those of the mature plant,. Fig. 231. Older sporophyte that lias developed two roots, r, and is un-folding the second leaf, /. but still attached to the withering gametophyteor prothallium. p; rh, rhizoids. DEVELOPMENT OF PLANTS 303 but as the stem elongates, new leaves are formed which gradu-ally become larger and each succeeding one resembles moreclosely the adult form. The foot disappears with the witheringof the gametophyte, and this is soon the fate of the primary root,but numerous secondary roots are formed along the stems as itcontinues to creep along on or near the surface of the soil. Thisgrowth goes on from two to several years before the plant isprepared to develop sporangia upon the leaves, page 254. Order 3. Equisetales. The Horsetail Ferns 114. General Characters.—This small group of ferns, com-prising but a single genus of about twenty-five species, is but aremnant of an extensive group of plants that flourished in thecoal period and that formed conspicuous features of the vegeta-tion at that ti
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