Rhodora 57:139. 1955.
Herbs, annual or perennial, stout, to 70 cm; rhizomes present. Leaves emersed or submersed; submersed leaves mostly absent; petiole terete to triangular, 2–36 cm; blade with translucent markings present as distinct lines, elliptic, lanceolate, or ovate, 2.6–15.5 ´ 0.5–20 cm, base truncate or occasionally cordate to tapering. Inflorescences racemes, rarely panicles, of 1–9 whorls, each 1–3(–4)-flowered, erect, 1.5–40 ´ 1.7–50 cm, not proliferating; peduncles 3–5-ridged, 2.1–57 cm; rachis triangular; bracts distinct, lanceolate, 0.3–2.5 cm, coarse, margins scarious; pedicels spreading to ascending, 0.6–2.8 cm. Flowers 6–11 mm wide; sepals spreading to recurved, 9–13-veined, veins not papillate; petals clawed; stamens 9–15; anthers versatile; pistils 45–200. Fruits oblanceolate, plump, 3–5-ribbed, abaxially 2-keeled, 0.9–3.2 ´ 0.6–2.5 mm; glands 1–2; beak terminal, 0.6–1.3 mm. 2n = 22.
Phenology: Flowering mid summer–fall.
Habitat: Clay soils of wet ditches, streams, and shallow ponds
Elevation: 0–800 m
Ark., Calif., Fla., Ill., Iowa, Kans., La., Mo., Nebr., Nev., Ohio, Okla., S.Dak., Tex., Utah, Wis., Mexico, West Indies, South America.
Echinodorus berteroi is an extremely easy species to recognize when in fruit. The elongated beaks of the fruits project upward, giving the fruiting head an echinate appearance. The generic name, in fact, came from the fruiting head of this species.