Rep. (Annual) Missouri Bot. Gard. 16:102. 1905.
Herbs, perennial, to 70 cm; rhizomes absent; stolons present; corms present. Leaves emersed; petiole terete-ridged, to 39 cm; blades sagittate, 5–20 × 2–8 cm, basal lobes equal to or less than remainder of blade. Inflorescences racemes or panicles, of 5–12 whorls, emersed, 25–30 × 6–15 cm; peduncles to 45 cm; bracts distinct or if connate, then less than ¼ total length, long-acuminate, 10–40 mm, firm, not papillose; fruiting pedicels spreading to ascending, cylindric, 1–2.5 cm. Flowers to 3.5 cm diam.; sepals recurved to spreading, not enclosing flower; filaments cylindric, longer than anthers, glabrous; pistillate pedicellate, without ring of sterile stamens. Fruiting heads (1.2–)1.5–2.5 cm diam.; achenes cuneate-obovoid, without abaxial keel, 2.1–3.1 × 1.4–2.2 mm, beaked; faces ??, wings 0–2, ± entire, glands absent; beak lateral, ascending apically, 0.4–1.7 mm. missing datum is whether faces are tuberculate or not; if datum is not easily available, change wording to near-original "faces with 0–2 wings."
Phenology: Flowering summer (Jul–Sep).
Habitat: Slightly basic to slightly acidic to alkaline waters of ponds, lakes, and swamps
Elevation: 100–�1800 m
Sask., Ala., Ark., Calif., Colo., Ill., Ind., Iowa, Kans., Ky., La., Mich., Minn., Miss., Mo., Nebr., Ohio, Okla., S.Dak., Tex., Va., Wis.