Add to ORKGPerennial, palustrial or aquatic herbs with a creeping rhizome; stems erect, solid, submerged at the base. Leaves biseriate, partly radical or subradical, partly cauline, lower congested, higher remote, elongate-linear, rather thick and spongy, bluntmargined; their sheathing bases excreting slime on their inner side. Flowers very numerous, very closely packed in 2 or less often 3, superposed, contiguous or more or less remote terete unisexual spikes; upper spike male; the 1-2 lower ♀; all spikes at the base with a foliaceous bract which falls off long before anthesis; the ♀ spikes here and there between the flowers often with a similar bract. ♂ Flowers consisting of 3 flat hairs together surrounding 2-5 stamens; anthers basifixed, linear, 2...