Rhizomes present. Cauline stems terete, often rusty spotted, 6--110 cm; nodal glands absent. Turions absent. Leaves both submersed and floating or floating absent, ± spirally arranged. Submersed leaves petiolate, lax; stipules persistent, conspicuous, convolute, free from blade, light brown, not ligulate, 1.5--11.7 cm, not fibrous, not shredding at tip, apex acute; petioles terete, 0.9--11.5 cm; blade light to dark green, ovate to oblanceolate, distinctly arcuate, 5--12.5 cm ´ 15--58 mm, base rounded to acute, without basal lobes, not clasping, margins entire, crispate, apex not hoodlike, acute to round-apiculate, lacunae absent; veins 19--49. Floating leaves: petioles continuous in color to apex, 2.3--22.6 cm; blade adaxially light green, lanceolate to round elliptic, 4.3--9.2 cm ´ 25--38 mcm, base rounded to cordate, apex acute to rounded; veins 27--49. Inflorescences unbranched, emersed; peduncles not dimorphic, terminal or axillary, erect, cylindric, 4.5--22.3 cm; spikes not dimorphic, cylindric, 34--65 mm. Fruits sessile, reddish brown, obovoid, turgid, abaxially keeled, laterally ridged, 5--6.7 ´ 4.5--5.2 mm, lateral ridges without points; beak erect, 0.5--0.8 mm; sides without basal tubercles; embryo with full spiral. 2n = 52.
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Stem elongate, usually simple; principal submersed lvs falcately folded, 25–37-veined, 8–20 cm, on petioles 1–6 cm, acute at both ends, the lower lanceolate, 2 cm wide, the upper gradually wider; floating lvs elliptic, 5–10 cm, half as wide, obtuse, rounded at base, many-nerved, on petioles 8–20 cm; stipules axillary, free, open, 2-keeled, 3.5–12 cm, tapering to a sharp slender point; peduncles stout, 8–20 cm, somewhat clavate, 3–4 mm thick at the top; spikes dense, 2–5 cm; frs obliquely obovoid, 4–5.5 mm (incl. the 1 mm beak), with 3 low, rounded keels; 2n=52. Ponds and lakes; Que. to B.C., s. to Ala. and Calif.
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