Description: Monoecious perennial herbs, of fresh waters. Rhizomes absent; stolons floating on or suspended in water, rooted or not, unbranched.
Leaves basal, emergent or floating, blade elliptic to orbiculate; apex obtuse to acuminate, base reniform or cordate; undersurface smooth on emergent leaves or with spongy, honeycomb-like aerenchymous tissue on floating leaves; petiolate.
Inflorescences cymose, sessile or short-pedunculate; spathe not winged. Flowers unisexual, male and female on same plant, emersed, pedicellate. Petals greenish white to yellowish. Male flowers with filaments connate at least 1/2 their length; anthers elongate. Female flowers with ovary 1-locular, falsely 6–9-locular; styles 3–9, 2-fid nearly to base.
Fruit berry-like, ellipsoid to spherical, smooth to ridged, dehiscing irregularly. Seeds ellipsoid, echinate, numerous.
Distribution and occurrence: World: 2 species, North America, Central america, South America. Australia: 1 species (naturalised).
Derived from the Greek word limnobios meaning living in pools.
|One species in NSW: Limnobium laevigatum|