3. Heteranthera Ruiz & Pavon, Fl. Peruv. Prodr. 9, plate 2. 1794.
Mud plantain [Greek heteros, different, and antheros, anther]
Eurystemon E. J. Alexander; Heterandra Palisot de Beauvois; Schollera Schreber; Zosterella Small
Herbs, annual or perennial, rooting in mud. Vegetative stems submersed and growing to surface, or emersed and procumbent or short. Flowering stems submersed and growing to water surface, or emersed. Sessile leaves submersed, forming basal rosette, or emersed on elongate stem; blade linear or sometimes oblanceolate, apex acuminate to obtuse. Petiolate leaves floating or emersed; blade reniform, cordate, or oblong, membranous, apex acute to obtuse. Inflorescences spicate or solitary, 1–30-flowered, elongating over 1–several days; spathes folded or clasping, with acute to caudate apex, or rarely expanded leaflike extension. Flowers: individuals open 1 day only; perianth with tepals connate 1/2 or more of its length, yellow, blue-mauve, mauve, or white, tubular or salverform, limb lobes linear to oblanceolate or narrowly elliptic, shorter than 2 cm, apex obtuse to acuminate; stamens 3, unequal, 2 lateral ones usually shorter; filaments yellow or purple, inflated in some species, glabrous, glandular-pubescent, or pilose; anthers yellow or purple, rounded, oblong, or sagittate; ovary incompletely 3-locular; ovules 10–many; style 3-lobed. Fruits capsular, elongate. Seeds 10–200, ovoid, testa with longitudinal wings.
Species 12 (7 in the flora): Western Hemisphere, Africa
In the flora area, Heteranthera peduncularis Bentham is known only from one collection in Arizona (C. Mohr s.n., US), probably from about 1900. The center of the distribution of this species is in the highlands of Mexico. It is closely related to Heteranthera multiflora and H. reniformis, and may be distinguished by distinctly cordate leaves, mauve perianth limb lobes, and glabrous filaments.
Horn, C. N. 1988. Developmental heterophylly in the genus Heteranthera (Pontederiaceae). Aquatic Bot. 31: 197–209.