The World Flora Online

Herbs, perennial, not stranded by low tide. Leaves submersed and emersed; submersed leaves sessile, blade linear; emersed petiolate, blade hastate to sagittate. Inflorescences of 1--15 whorls, floating or emersed; bracts connate. Flowers: pistillate without ring of sterile stamens; petals with purple spot at base.

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Perennial. Leaves typically emersed, sagittate with linear to ovate blades and somewhat divergent basal lobes, rarely submerged or floating, then the basal lobes absent. Scapes with 3-12 whorls of flowers, simple or branching at the lowest whorl. Bracts connate, the free ends elongate attenuate, to 2.5 cm long. Pistillate flowers rarely with a ring of functional stamens; sepals covering more than one-half of the receptacle at maturity; petals with a purple spot at base. Stamens numerous, the linear sparsely pubescent filaments 1.8-3.5 mm long. Mature pistillate heads 1.5-2.5 cm in diameter; achenes 2-3 x 1-1.5 mm, the resin duct present or obsolete.

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Bracts united. Staminate flowers without ring of sterile carpels. Carpellate flowers with corollas with purple spot at base; gynoecium without ring of sterile stamens.

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Warm-temperate South America, east of the Andes; sporadically northward in the tropics to coastal Ecuador; introduced or adventive elsewhere. Collections examined from Argentina, Bolivia, Brazil, Ecuador, Paraguay, Peru and Uruguay. Adventive but apparently not persisting along the coast of the southeastern United States. Cultivated in many botanical gardens throughout the world including Africa, Java, and the United States.

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Ecuador and Peru to southeastern Brazil, Uruaguay, and northern Chile.

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