. A textbook of botany for colleges and universities ... Botany. Si8 ECOLOGY. form as in root hairs, and (2) the observed rise of colored fluids and the crystallization within the rhizoids of the Marchantiaceae of absorbed salts (as Berlin blue). The special advantage of the peg rhizoids, though much discussed, is not known. Moss rhizoids. — Structure and habitat variation. —Moss rhizoids commonly are brownish, branched, multicellular cell filaments with oblique cross walls. Often they have a rootlike aspect, by reason of a strong central trunk with small lateral branches (figs. 747, 748). Som
. A textbook of botany for colleges and universities ... Botany. Si8 ECOLOGY. form as in root hairs, and (2) the observed rise of colored fluids and the crystallization within the rhizoids of the Marchantiaceae of absorbed salts (as Berlin blue). The special advantage of the peg rhizoids, though much discussed, is not known. Moss rhizoids. — Structure and habitat variation. —Moss rhizoids commonly are brownish, branched, multicellular cell filaments with oblique cross walls. Often they have a rootlike aspect, by reason of a strong central trunk with small lateral branches (figs. 747, 748). Some mosses (as Ftinaria) de- velop very long rhizoids in solutions deficient in nitrogen or phosphorus. Rhizoids develop abun- dantly on the aerial stems of some mosses (as Thu- idium) when grown in a moist atmosphere; such rhizoids are as brown as those developed in the soil in spite of the exposure to light (figs. 749, 750). Rhizoids are developed abundantly also in xerophytic mosses, and sometimes in mosses that frequent running waters, while they are poorly developed or wanting in pond and swamp mosses. In dry soil Polytrichum juniperinum exhibits a vigorous development of soil rhizoids, but in swamps these are largely replaced by aerial rhi- zoids ("stem felts"). Usually rhizoids are better developed in erect mosses which have prominent " vascular" tracts, and which grow somewhat separately (as Polytrichum, Catharinea, and Mnium) than in mosses without such tracts, which grow in dense cushions or mats (as Leucobryum, and Sphagnum, which has no rhizoids). Role. — Most moss rhizoids clearly are organs of anchorage, though the stem felts common in swamps and in moist woods are of no importance in this respect. The scantiness of experimental data makes it impossible to speak in general terms concerning the efficiency of the rhizoids in absorption. Probably mosses like Polytrichum, which grow as detached individuals and pos- sess "vascular''strands
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1910
