• (n.) The rootstock or decumbent stem by which a hydroid is attached to other objects. See Illust. under Hydroidea.
Hy`dro·rhi'za noun ; plural Latin Hydrorhizæ , English Hydrorhizas . [ New Latin , from English hydra + Greek ... a root.] (Zoology) The rootstock or decumbent stem by which a hydroid is attached to other objects. See Illust. under Hydroidea ....
the rootlike base of a hydroid colony, by which it is attached to the substratum.