Dicraeanthus

Herbs attached to rocks in fast-flowing freshwater; basal part thalloid, bearing long simple or branched branches floating in current. Leaves alternate, arranged all along branches at regular intervals, usually +/- dichotomously divided. Flowers arranged in pedicelled or sessile inflorescences, either on main branches or on short branches in leaf axils; spathellas each enclosing an inverted flower, ovoid or ellipsoid, opening irregularly from the apex; pedicel far exserted after anthesis. Tepals 2. Stamens 2, surrounded by tepals, usually shorter than ovary; filaments fused in basal part; anthers introrse; pollen in diads. Ovary unilocular, very narrowly ellipsoid, borne on a well-developed gynophore; placenta central; ellipsoid, bearing many anatropous ovules; stigmas 2, conical; slightly fused at base. Capsule 8-ribbed, dehiscing by 2 equal valves remaining attached at apex. Seeds many, small, with reticulate testa.