​Rhizoids (rī′zoids). Usually hair-like outgrowths from plant-bodies which act as holdfasts and, often, as absorbing organs. The name means root-like, but the similarity is by no means one of structure, but rather one of general function in relation to the outside world. Rhizoids are mostly developed by the lower plants, as, for example, in connection with the anchoring of sea-weeds, on the underside of the thallus-bodies of liverworts, from the base of the erect moss-plants, from the under side of the prothallium of ferns etc.