Geniculate (alga)

A geniculate habit, with reference to the red algae, is one in which the alga branches, tree-like, forming "fronds" that attach to the substrate with a holdfast. Non-calcified "genicula" serve as "knees" or hinges between the calcified intergenicula. The geniculate or non-geniculate form of algae was used to classify them; however either form has been convergently derived many times. The genuculae sometimes contain lignin.