A family of aquatic monocotyledons comprising slender plants that have submerged, linear, opposite to whorled leaves with sheathing bases. The flowers are minute and unisexual. The male flower consists of 1 stamen in a 2-lipped perianth, the female of 1 carpel which is usually without perianth. The fruit is a tiny nut. There is 1 genus and 35 species, occurring in temperate and humid tropical regions.
Subjects: Plant Sciences and Forestry.