Fruit a combination of the fleshy inner bract and two fertilized ovaries, one usually abortive, often germinating while still attached to the plant; seedling free-floating.
Pistillate flower of 2 free ovaries, each with short style and long coiled stigmas
Staminate flower of 2 anthers, dorsally connate over their length, attached at same height, each with terminal appendage; pollen filamentous
Flowers solitary and terminal on short lateral shoots, subsessile, enclosed by 4 leafy bracts
Leaves with sheath compressed, ligulate and auriculate, amplexicaul, shed together with leaf, scar closed; bladelinear, margin spinulose, apex denticulate
Stem and branches bearing a terminal cluster of leaves
Submerse aquatic herbs; rhizome robust, woody, creeping, sympodial, with 1– 2 erect unbranched or little-branched stems at every 4th internode; roots (1– )2(– 5), ± branched, only on the internode preceding the stem-bearing internode