Species commonly cultivated
Callitriche heterophylla Pursh (North America)
C. palustris L. (North America, Europe)
C. stagnalis Scop. (North America, Europe, Asia, Australasia)
C. verna L. (North America)
Cosmopolitan distribution makes determination of new introductions difficult.
rarely weedy in rice crops
Annual or perennial. Stems elongate when submersed or compact when emersed. Leaves opposite, decussate, in a terminal rosette when floating, sessile; leaf blade linear to oblong to spathulate, only midvein prominent; apex often (unequally) notched; margin entire. Flowers minute, solitary, axillary, unisexual; petals and sepals absent; male flower with a single stamen as an elongate filament with reniform anther; female flower with 2 elongate styles. Dispersal by stem fragments or seed.
lakes, ponds, and slow flowing rivers