. Plant life, considered with special references to form and function. Plant physiology. VEGETA TIJ'E REPROD UCTIOX. 227 320. The sporophyte.—Among the niossworts, feinworts, and seed jilants reproduction by non-sexual spores has be- come so fixed and important that one stage in the plant is devoted especially to producing them. This phase is diflerent from that producing sexual cells, the differ- ence becoming greater the more complex the plant. The stage set apart for spore production is called the sporophyte. In the moss- worts the sporophyte has very little green tissue, and therefore carr
. Plant life, considered with special references to form and function. Plant physiology. VEGETA TIJ'E REPROD UCTIOX. 227 320. The sporophyte.—Among the niossworts, feinworts, and seed jilants reproduction by non-sexual spores has be- come so fixed and important that one stage in the plant is devoted especially to producing them. This phase is diflerent from that producing sexual cells, the differ- ence becoming greater the more complex the plant. The stage set apart for spore production is called the sporophyte. In the moss- worts the sporophyte has very little green tissue, and therefore carries on little nutritive work, but depends for its supply of food chiefly upon the sexual stage, ^yith which it is connected throughout its entire existence (^ 68). In the fernworts and seed plants, however, the sporophyte i)Ossesses extensive nutriti\'e tissues, the leaves, stems, and roots belonging entirely to this stage. Sporangia in these plants- may be formed either upon the stem or the leaves —never upon the roots. 321. Liverworts. — In the li\-erworts the sp)orangium is gen- erally produced at the upper end of a short or long stalk. It is either spherical, o\'oid, or short- cylindrical (figs. 64, 65). The "^' spore-producing tissue occupies the greater part of the interior, the wall being formed usually by a single layer of. P^iG. 229.—\ brancli of a red sea- \s eed (l\Tlysi/'hi>iua <^/'iZi\t), show- ing tctraspores, /, formed bv an internal cell of tlie thallus. ^Iag- nified about loodiam.—.\fterRiJtz. 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, H. Holt & company
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