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Main portion of the lf-blade mostly lanceolate, sometimes broader, mostly 5–20 × 2–8 cm, 0.8–8 times as long as wide; petiole corrugated in x-section, at least in the lower half; infl often branched at the lowest whorl; fls in 5–12 whorls; bracts 1.5–4 cm, equaling or longer than the 1.3–2.5 cm pedicels, stramineous, papery-firm, broad-based and long-attenuate; fruiting head usually oblate-spheroidal; receptacle not markedly echinate; achenes 2–3 mm, lacking resin-ducts, with a short wing (not extending into the beak) on one or both faces, or the faces wingless; dorsal wing entire to crenulate, usually truncate at the top and not confluent with the beak; ventral wing narrower and confluent with the beak; beak 0.4–1.7 mm; 2n=22; otherwise much like no. 4 [Sagittaria engelmanniana J. G. Sm]. In circumneutral to somewhat alkaline shallow water of ponds and swamps; O. and Mich. to Minn. and S.D., s. to Tenn., Ala., and Tex. July–Oct. (S. engelmanniana var. b.)
Aquatic, perennial herb. Emergent leaves sagittate, 4.5–10 cm long, 0.2–2 cm wide; basal lobes linear to attenuate. Inflorescence with 2–4 pseudowhorls of flowers. Bracts 0.5–1.2 cm long. Pedicel of female flowers ascending, 1.5–3.5 cm long. Outer perianth lobes reflexed, 0.4–0.7 cm long; inner perianth white, nearly twice as long as outer perianth. Filaments of male flowers glabrous. Achene 2.3–3.2 mm long, 1.6–2.3 mm wide; surface unadorned or with 1 or 2 narrow wings; apex with persistent base of style (0.7–) 1.0–1.5 mm long.
