. Outlines of plant life : with special reference to form and function . Botany. CHAPTER VII. FERNWORTS AND SEED-PLANTS. Fernworts. Among the still more complex plants, the ferns and their allies, the same "alternation of generatiotis " can be seen. The two "generations," or phases, have, however, changed much in relative size. Whereas in the liverworts and mosses the gametophyte is much the larger and more conspicuous, as well as the longer-lived, among fernworts the sexual phase is so much smaller that it is seldom seen; and in some species it is almost microscopic. On th
. Outlines of plant life : with special reference to form and function . Botany. CHAPTER VII. FERNWORTS AND SEED-PLANTS. Fernworts. Among the still more complex plants, the ferns and their allies, the same "alternation of generatiotis " can be seen. The two "generations," or phases, have, however, changed much in relative size. Whereas in the liverworts and mosses the gametophyte is much the larger and more conspicuous, as well as the longer-lived, among fernworts the sexual phase is so much smaller that it is seldom seen; and in some species it is almost microscopic. On the other hand, the sporophyte is the phase which is usually seen and the only part popularly known. 63. The gametophyte. — The vege- tative body of this phase of the fern- worts in its best developed forms is a small, flattened, green body of oblong, orbicular, or cordate outline, commonly less than half a centimeter in diameter, rarely as much as 2 cm. (fig. 48). It is strikingly like a thallose liverwort in general form, being distinctly dorsiventral and having rhizoids on its under side, which fasten it in place. Only the central part of the gametophyte consists of more than one layer of cells. On the under side of this central '' cushion," as it is called, are borne the sex organs. 53. Fig. 48,—Ventral side of the gametophyte of a fern, Aspleniutn, The notched end is the an- terior. Rhizoids near posterior end. The small circles show position of male organs ; the chim- ney-like projections near anterior end the female organs. Magnified jo diam.—After 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 Barnes, Charles Reid, 1858-1910. New York : Henry Holt and Company
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