Family Pontederiaceae
Description: Annual or perennial, free-floating, rhizomatous or stoloniferous aquatic herbs.
Leaves alternate, sheathed, often stipulate, often with a petiole-like stalk between the sheath and the expanded blade; blade hair-like to circular, base cuneate to cordate.
Inflorescence spike-like, paniculate or flowers solitary, subtended by 2 spathes. Flowers bisexual, sometimes heterostylous, actinomorphic or zygomorphic. Perianth lobes usually 6, variously fused, petaloid, white, blue or yellow. Stamens 6, 3 or 1, similar or dissimilar, inserted on perianth; anthers 2-locular, introrse, dehiscing by longitudinal slits or rarely apical pores. Ovary superior, 3-locular though sometimes only 1 fertile; style 1.
Fruit a capsule or 1-seeded nutlet; seeds numerous or solitary.
Distribution and occurrence: World: 2 genera, c. 40 species, America, Africa, Asia, Australia. Australia: 2 genera, 6 species, all mainland States.
External links:
Angiosperm Phylogeny Website (Family: Pontederiaceae, Order: Commelinales)
Wikipedia Key based on Pellegrini et al. 2018.
Text by S. W. L. Jacobs (edited P. Lu-Irving 2026)
Taxon concept: Pellegrini et al. 2018, Pellegrini 2017
| | Key to the genera | |
| 1 | Petiolate leaves present or absent, if present, base of petiole not swollen; stamens (1-)3 | Heteranthera |
| Petiolate leaves present, base of petiole swollen; stamens 6 | Pontederia |
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