Hygrophila R. Br.
hygrophila, water wisteria, Indian plant, blue stricta, hygro
Asia, South America, Africa
Species commonly cultivated
Hygrophila angustifolia R. Br. (Australia, Papua New Guinea)
H. balsamica (L.) Raf. (India, Sri Lanka)
H. corymbosa (Blume) Lindau (Southeast Asia)
H. difformis (L.) Blume (India, Burma, Thailand, Malaysia, Australia)
H. guianensis Nees (Guyana, Venezuela, Bolivia)
H. polysperma (Roxburgh) T.Anderson (India, Bhutan, Central and North America)
U.S. Federal Noxious Weed: Hygrophila polysperma
Identification: The submersed form of Hygrophila polysperma can be distinguished by its short to medium, typically light green leaves with round apices. (Variegated cultivars exist.) The emersed form is more difficult to identify, but has small sessile flowers, small emersed leaves, and a capsule bearing numerous seeds.
Hygrophila polysperma is introduced into Mexico and southeastern United States. Hygrophila difformis is introduced into northern Australia.
Perennial. Stem creeping or erect, rooting at lower nodes. Leaves opposite, decussate, sessile or petiolate; leaf blade entire to dissected to various degrees, lanceolate to ovate; margin sometimes serrate, sometimes highly heterophyllous between submersed and emergent forms. Inflorescence solitary to racemose, axillary. Flowers sessile or pedicellate; sepals 5, fused or distinct; corolla 5-lobed, lobes equal or 2-lipped, with adaxial lip 2-lobed, abaxial lip 3-lobed, white to yellow, purple. Dispersal by stem fragments or seeds.
rivers, lakes, and wetlands