In some cases the rhizoids are united together into larger strands, the rhizines.
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.
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.
The base of the stem bears numerous cell-filaments (rhizoids) which fix the plant to the substratum upon which it is growing.