Greek isos, equal, + etes, year, alluding to the green leaves of some species that persist throughout the year.
Plants tufted, grasslike, aquatic, emergent, or terrestrial. Rhizomes 2- to 3-lobed, cormlike, bearing a cluster of spirally arranged leaves above and roots below. Leaves linear, round, grasslike, tapering toward tips, bases spoon-shaped because of overlapping membranous margins, with small triangular flaps (ligules) on inner surfaces at points where leaves narrow. Sporangia solitary, large, variable in size and shape, borne in cavities on inner sides of leaf bases below ligules, heterosporous.
A genus of 60 to 150 species found worldwide. Represented in Hawai'i by a single geographically and ecologically restricted endemic species.
