Echinodorus

Echinodorus
Echinodorus grisebachii in an aquarium
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Monocots
Order:	Alismatales
Family:	Alismataceae
Genus:	Echinodorus Richard ex Engelmann in A. Gray, 1848

Echinodorus (burhead or Amazon sword plant) is a genus of plants in the family Alismataceae and distributed in the Western Hemisphere from the central United States to Argentina. Its scientific name is derived from Ancient Greek echius – rough husk, and doros – leathern bottle, alluding to ovaries, which in some species are armed with persistent styles, forming prickly head of fruit. Some of the species are commonly cultivated in artificial aquatic habitats.

The plants areannual or perennial, growing emersed, floating-leaved, or seasonally submersed, leaves glabrous to stellate-pubescent; rhizomes present or absent; stolons absent; corms absent; tubers absent. Roots not septate. Leaves sessile or petiolate; petioles triangular, rarely terete; blade with translucent markings as dots or lines present or absent, linear to lanceolate to ovate, base attenuate to cordate, margins entire or undulating, apex obtuse to acute. Inflorescences racemes or panicles, rarely umbels, of 1–18 whorls, erect or decumbent, emersed; bracts coarse, apex obtuse to acute, surfaces smooth or papillose along veins, apex obtuse to acute. Flowers bisexual, subsessile to pedicellate; bracts subtending pedicels, subulate to lanceolate, shorter than to longer than pedicels, apex obtuse to acute; pedicels ascending to recurved; receptacle convex; sepals recurved to spreading, herbaceous to leathery, sculpturing absent; petals white, entire; stamens 9–25; filaments linear, glabrous; pistils 15–250 or more, spirally arranged on convex receptacle, forming head, distinct; ovules 1; style terminal or lateral. Fruits plump, often longitudinally ribbed, sometimes flattened, rarely abaxially keeled, abaxial wings absent, lateral wings absent, glands often present.

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