Rhizoids are protuberances that extend from the lower epidermal cells of bryophytes and algae.
They are similar in structure and function to the root hairs of vascular land plants.
[1] Plants originated in aquatic environments and gradually migrated to land during their long course of evolution.
In vascular plants, they are often called root hairs and may be unicellular or multicellular.
[4] In fungi, rhizoids are small branching hyphae that grow downwards from the stolons and anchor the fungus to the substrate, where they release digestive enzymes and absorb digested organic material.