. Outlines of plant life : with special reference to form and function . Botany. 36 OUTLINES OF PLANT LIFE. which so softens or dissolves the cell-walls of the host that they penetrate these cells readily, not only at the surface (j/', sp", fig. 32), but in the interior.* They then branch freely, often growing in the spaces between the cells, often passing through the cells themselves (fig. j,'^. Plants are often attacked when mere seedlings. From either a bit of my- celium or a spore that has survived the winter or the dry season, a hypha grows, which, almost as soon as the seedling emer
. Outlines of plant life : with special reference to form and function . Botany. 36 OUTLINES OF PLANT LIFE. which so softens or dissolves the cell-walls of the host that they penetrate these cells readily, not only at the surface (j/', sp", fig. 32), but in the interior.* They then branch freely, often growing in the spaces between the cells, often passing through the cells themselves (fig. j,'^. Plants are often attacked when mere seedlings. From either a bit of my- celium or a spore that has survived the winter or the dry season, a hypha grows, which, almost as soon as the seedling emerges from the seed, pene- trates it. The fungus, in these cases, may develop quickly and kill the young plant (as in the "damping off" disease in greenhouses), or it may develop slowly and not reach its maturity until the host is also mature. 46. Haustoria.—Those fungi which grow upon the surface of living plants (and those which grow in the internal air-spaces) often have special branches for fastening themselves to the host or Fig. Hypha of T-ra- absorbing food from it. In the surface tnftes Pini perforating at c . the walls ot a wood-cell of fungi these are usually very short, disk- Scotch pine and destroying the primary wall of the cell, like Or lobcd branches which do not (/, e, holes made by hyphse. Magnified about 800 diam. penetrate the cclls of the host. In —After R. Hartig. Other cases they are branches of minute diameter, which enter the cells, and either enlarge into a knob (fig. 34) or branch profusely (fig. 35).. * The penetration of cell-walls is probably assisted by such pressure as the growing hypha can 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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