herbs, with slender, elongated, branched stems. Plants monoecious or dioceous.
Leaves verticillate, or lowermost opposite, sessile, linear to narrowly
elliptic. Flowers unisexual, axillary. Male flowers : solitary,
short-pedicelled, in a subgobose, muricate spathe, flowers free from spathe on
water surface at anthesis, sepals 3
convex, petals 3 narrower than sepals, oblong or cuneiform, stamens 3.
Female flowers : solitary in a tubular, 2-tooted spathe, sepals and petals similar
to male ones, ovary cylindric, beaked, ovules few. Fruit smooth or muricate.
Seeds 2-6, oblong-elliptic.