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THE OAK.
as a thin sheet of closely-woven hyphæ continuous over the whole of the tip, and sending processes in between the cells of the dermatogen, but not into the cavities of the cells nor deeper into the tissues. Loose hyphæ also
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Fig. 25.—Longitudinal section of the tip of one of the roots marked m in Fig. 7, the outer layers of which are infested with fungus hyphæ, f (mycorhiza); r.c, root-cap; m, embryonic tissue from which all originates; P, pith; sp, spiral vessels of the primary xylem; c, cortex.
radiate into the soil around, and often simulate the root-hairs of other plants, which, in fact, they are said to replace (Fig. 25, f). These hyphæ are extremely fine
