Aquatic or wetland annual or perennial herbs. Leaves sessile or petiolate; leaf-blades linear, elliptic or ovate, attenuate, truncate, rounded or cordate at base, entire to crenate-dentate, erect and more or less isolateral or sometimes dotted beneath. Inflorescence an erect open panicle or a dense head. Flowers heterostylous, pedicellate or sessile; corolla yellow or white, conspicuously fimbriate at the throat, lobes rarely with a longitudinal keel on inner surface, margins entire or serrulate; ovules 5–10 per placenta. Capsule globose, ovoid, or ellipsoid, opening by 4 apical valves, ripening in the air. Seeds orbicular or ellipsoid, with or without a conspicuous caruncle.
An endemic Australian genus of 7 species.