Home
Perennial aquatic or marsh herbs. Leaves erect; leaf-blade linear-lanceolate to ovate; apex acute; base decurrent to cordate. Inflorescence compound, pyramidal; flowers and branches in whorls of 4 or more, each whorl subtended by 3 bracts and several smaller bracteoles. Flowers bisexual. Sepals 3, appressed in the fruiting state. Petals 3, larger than the sepals. Stamens 6; filaments filiform. Carpels many, free; style ventral, erect or curved; stigma papillose; ovules solitary, basal. Achenes many, in a whorl on the flat receptacle, compressed laterally, ridged dorsally.
Perennial, emergent, aquatic herbs with erect basal stems from a shortened stem or corm. Leaves emergent on long petioles; blade linear to ovate. Inflorescence on a leafless peduncle, paniculate, with whorls of 3 or more branches subtended by bracts. Flowers bisexual. Sepals 3, green. Petals 3, white to dark pink. Stamens 6. Carpels numerous, free, often closely packed, in 1 whorl, laterally flattened, rounded on back, not triangular, 1-ovuled; style lateral. Achenes numerous, laterally compressed, 1-seeded, produced in a densely packed whorl.
Perennial aquatic herbs, rarely submersed. Leaves erect, plantain-like, or rarely floating, long-petioled. Inflorescence a much-branched, pyramidal panicle; each branch with 2-3 papery basal bracts. Flowers many, pedicellate; each pedicel bracteate at base; sepals 3, green, persistent; petals 3, > sepals, white or occasionally rose or pink. Stamens 6-9. Achenes free, numerous, in a single whorl round flattened receptacle. Spp. c. 9, in north temperate regions and Australia. Adventive spp. 2.
Herbs, aquatic or of marshes, usually with a tuber. Leaves aerial, floating, or submerged, all basal, petiolate, margin entire. Inflorescences paniculate or occasionally umbellate; branches whorled, each one usually secondarily branched and with bracts at base. Flowers bisexual. Petals usually larger than sepals. Stamens 6. Carpels numerous in a single whorl, free, each with 1 ovule. Achene laterally compressed, 1-or 2-grooved or canaliculate abaxially, with a usually adaxial beak.
