. Botany of the living plant. Botany. 196 BOTANY OF THE LIVING PLANT Sarcodes) (Fig. 148). In the last-named, which is a complete sapro- phyte native of the Western States of America, the root-cap is shed off in layers, which are held in the fungal weft. This closely invests the superficial cells of the root, forcing them apart; but still they appear healthy and active. The fungal filaments do not as a rule penetrate the cells themselves, so that the investment is external. It is, however, so complete when fully developed that the surface of the root has no direct contact with the soil, and ta
. Botany of the living plant. Botany. 196 BOTANY OF THE LIVING PLANT Sarcodes) (Fig. 148). In the last-named, which is a complete sapro- phyte native of the Western States of America, the root-cap is shed off in layers, which are held in the fungal weft. This closely invests the superficial cells of the root, forcing them apart; but still they appear healthy and active. The fungal filaments do not as a rule penetrate the cells themselves, so that the investment is external. It is, however, so complete when fully developed that the surface of the root has no direct contact with the soil, and takes its supolies through the medium of the fungus. The hyphae at the outer surface grow out into absorptive filaments that take the place of the Fig. 148. Part of the superficial tissue of a root of Sarcodes, covered by a dense felt of fungal hyphae {h), in which the dark lines (r, c) are the layers of the root-cap. The outermost layer of cells of the cortex (c) is covered by a piliferous layer {e), but the root-hairs are replaced by conical cells between which the fungal hyphae have forced their way. (After Oliver.) The native Monotropa hypopitys, which grows in woods of Fir and Beech, is also a complete saprophyte. Its only visible means of nutrition is from the decaying vegetable matter in which it lives, through the intermediary of the symbiotic fungus. This is found closely investing the surface of its roots, and occasionally penetrating the cells. In estimating the relations of the two parties to ectotrophic myco- rhiza in green plants, one essential fact is that it is not a necessary condition of the life of the tree, nor does the fungal investment neces- sarily cover the whole root-system. Experimental cultures have given contradictory results as to the benefit derived by the higher Plant. But certain general considerations seem clear. On the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for read
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1919
