. Plants and their uses; an introduction to botany . Fig. 343). The gametangia are completely embedded in the thallus(Fig. 344). The embryo (E) develops a somewhat expanded footwhich serves to hold the slender .sporophjte in an upright position,and functions also as an organ of absorption. As the sijorophyfecontinues to grow, however, it is plain that scarcely more thaninorganic materials arc taken in; for ver3 soon, above the foot ap-pears an elongating zone of tissue containing much chlorophyll;and this enables the sporophyte to photosynthesizc and ,so, unlikeour other liverworts, to be almo
. Plants and their uses; an introduction to botany . Fig. 343). The gametangia are completely embedded in the thallus(Fig. 344). The embryo (E) develops a somewhat expanded footwhich serves to hold the slender .sporophjte in an upright position,and functions also as an organ of absorption. As the sijorophyfecontinues to grow, however, it is plain that scarcely more thaninorganic materials arc taken in; for ver3 soon, above the foot ap-pears an elongating zone of tissue containing much chlorophyll;and this enables the sporophyte to photosynthesizc and ,so, unlikeour other liverworts, to be almost )orting. If an Antbero-ceros sporophyte should ever develop a root it would no longerneed to be even a partial parasite, as now, but could leafl an entirelyindependent Qxistence. The elongating region connecting the cap-sule and the foot is morphologically a shoot, and thus we have inthis little plant the beginnings of a differentiation into three mem-bers—sporangium, foot, and shoot. At thecenter of the shoot and THE TRUE MOSSES 519. Fig. 341, II.—Umljrella-liverwort. Archigonio- phores (f) bearing ripe fruit (sporophytes),the spore-cases of which are seen projectingbeyond the curtains which protected themwhile young. Two of the spore-cases haveburst showing the projecting elaters. (At-kinson.) extending into the capsule is a column of somewhat elongated cells,which is called the columella (Fig. 345, c, c). Breathing-pores atthe surface permit aeration of the inner cells. Hepatica? are plants producing archegonia upon a mostly prostrateand thalline gametophyte which may be variously lobed or branchedand often resembles a flattened leafy moss, but which generally haswell-contrasted upper and lower surfaces; and there is a sporaiigitwigenerally dehiscing longitudinally and discharging its spores by meansof intermingled thread-like elaters. There are about 3,000 species. 190. The true mosses (Class Musci). The name popularh given to any small, matted pla
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1913
