The primitive cell sends colorless tubelets (rhizoids, rh.) into the mud on which it grows.
Ax., Green axis creeping on the surface of damp soil; rh., colorless rhizoids penetrating the soil; asc. ax., ascending axes of green cells.
In certain types living on clamp soil, the rhizoids penetrate the substratum, and in addition to fixing the plant absorb food substances (dissolved salts) from the substratum (fig.
The formation of a massive body naturally involves the localization of the absorptive region, and the function of absorption (which in the simpler forms is carried out by the whole of the vegetative part of the mycelium penetrating a solid or immersed in a liquid substratum) is subserved by the outgrowth of the hyphae of the surface-layer of that region into rhizoids, which, like those of the Algae living on soil, resemble the root-hairs of the higher plants.
We may note the universal Li occurrence on the lower surface of the thallus of fixing ver and absorbing rhizoids in accordance with the terrestrial Worts.
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