Erect, emergent, annual or perennial herb, rooting in substrate. Leaves floating and/or emergent; petiole slender, with expanded, semi-transparent, membranous wings basally; lamina linear, or narrowly ovate to ovate, with base obtuse to cordate. Inflorescence erect, panicle-like, with flowers arranged in 1 to several successive pseudowhorls which are separated by a long axis; each pseudowhorl of 3–12 flowers and each flower subtended by a bract. Flowers bisexual; inner perianth whorl longer than outer; stamens 6, in pairs opposite outer perianth lobes; carpels 6–10, free. Aggregate fruit of 2-seeded follicles.
5 species from Europe, North Africa, Asia, North America; 1 species in Australia and Victoria.