2. Eichhornia Kunth, Eichhornia. 3. 1842.
Water-hyacinth, jacinthe d’eau [for Johann A. F. Eichhorn, 1779–1856, Prussian statesman]
Piaropus Rafinesque, name rejected
Herbs, annual or perennial, rooting in mud or free-floating. Vegetative stems submersed and growing to surface, or emersed and short. Flowering stems emersed. Sessile leaves forming basal rosette or alternate on elongate vegetative stem; apex acuminate. Petiolate leaves floating or emersed; blade cordate to ovate or round, coriaceous, apex obtuse. Inflorescences spicate, up to 30-flowered, elongating over several days; spathes folded, with acuminate to caudate extension. Flowers open 1 day only; perianth with tepals connate for more than 1/2 its length, blue, mauve, or rarely white, funnelform, limb lobes obovate to oblanceolate, longer than 2 cm, glandular-pubescent, apex obtuse to acute; stamens 6, distal 3 shorter than proximal 3; filaments curved upward near apex, purple, glandular-pubescent; anthers yellow, rounded to oblong; ovary incompletely 3-locular; ovules many; style 3-lobed. Fruits capsular, elongate. Seeds 10–200, ovoid, testa with longitudinal wings.
Species 7 (2 in the flora): introduced; Neotropics and Africa.
Eichhornia paniculata (Sprengel) Solms-Laubach [syn. Piaropus paniculatus (Sprengel) Small] was reported by J. K. Small (1913) as occurring in drainage ditches of peninsular Florida. The collection was made in 1907 in Manatee County (J. K. Small s.n., NY). This species can be recognized by its growing rooted in mud and by the presence of cordate leaves and an elongate flowering stem terminated by a panicule of 20–100 flowers.
Eichhornia diversifolia (Vahl) Urban, native to Puerto Rico, is not known to occur in the flora area.
Barrett, S. C. H. 1988. Evolution of breeding systems in Eichhornia (Pontederiaceae): A review. Ann. Missouri Bot. Gard. 75: 741–760.