4. Pontederia Linnaeus, Sp. Pl. 1: 288. 1753; Gen. Pl. ed. 5, 140. 1754.
Pickerel-weed [for Giulio Pontedera, 1688–1757, Italian botanist]
Narukila Adanson; Umsema Rafinesque; Unisema Rafinesque
Herbs, annual or perennial, rooted in mud. Vegetative stems submersed and growing to surface, or rhizomatous. Flowering stems submersed and growing to surface, or emersed and slightly constricted just below first node. Sessile leaves forming basal rosette, blade thin. Petiolate leaves floating or emersed; blade cordate to reniform, apex obtuse to acuminate. Inflorescences spicate, commonly 50 or more-flowered, elongating over many days; spathes folded, apex acute to acuminate; peduncle glandular-pubescent or pilose. Flowers open 1 day only; perianth mauve, blue, or white, funnelform, limb lobes oblong to oblanceolate, glandular-pubescent or pilose, apex obtuse to acuminate; stamens 6, distal 3 shorter than proximal 3; filaments purple, glandular-pubescent; anthers yellow, ovoid to oblong; ovary 3-locular, only 1 developing to maturity; ovule 1; style 1 or more. Fruits utriculate, ovoid, with spinulose, dentate or smooth longitudinal ridges. Seed 1, ovoid, smooth.
Species 6 (1 in the flora): Western Hemisphere.
SELECTED REFERENCES
Fernald, M. L. 1925. Pontederia versus Unisema. Rhodora 27: 76–81. Horn, C. N. and R. R. Haynes. 1987. Typification of Pontederia and its Linnaean species names (Pontederiaceae). Taxon 36: 621–625. Lowden, R. M. 1973. Revision of the genus Pontederia L. Rhodora 75: 426–487. Whigham, D. F. and R. L. Simpson. 1982. Germination and dormancy studies of Pontederia cordata L. Bull. Torrey Bot. Club 109: 524–528.
