Herbs, perennial, to 110 cm; rhizomes absent; stolons present; corms present. Leaves emersed, floating, and submersed; submersed phyllodial, flattened, to 45 cm; floating with petiole triangular, to 100 cm, blade cordate or sagittate, rarely linear or ovate, 7.5--9 ´ 3.5--4 cm; emersed with petiole recurved, 3.5--51 cm, blade linear to sagittate, 2.5--17 ´ 1.5--11 cm, basal lobes when present shorter than remainder of blade. Inflorescences racemes, rarely panicles, of 2--10 whorls, emersed, 14--21 ´ 2--10 cm, peduncle triangular, 10--50 cm; bracts connate more than or equal to ¼ total length, lance-attenuate or acute, mostly (4--)7--40 mm, membranous, not papillose; fruiting pedicels ascending, cylindric, 0.5--2 cm. Flowers to 25 mm diam.; sepals recurved, not enclosing flower or fruiting head; filaments not dilated, equal to or longer than anthers, glabrous; pistillate pedicellate, without ring of sterile stamens. Fruiting heads 0.8--1.5 cm diam.; achenes obovoid, abaxially keeled, 1.8--2.6 ´ 1.3--2.5 mm, beaked; face not tuberculate, wings 0--1, ± entire, glands 0--1; beak apical, erect, 0.1--0.4 mm. 2n = 22. Flowering late spring--summer (Jun--Sep). Calcareous and muddy shores and shallow waters of rivers, lakes, ponds, pastures, and ditches, occasional in tidal waters, or in deep flowing water with slow current; 100--2500 m; Alta., B.C., Man., N.B., Nfld. and Labr. (Labr.), N.W.T., N.S., Ont., Que., Sask., Yukon; Alaska, Ariz., Calif., Colo., Conn., Idaho, Ill., Ind., Iowa, Kans., Maine, Mass., Mich., Minn., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.Dak., Ohio, Okla., Oreg., Pa., S.Dak., Tex., Utah, Vt., Wash., Wis., Wyo. Sagittaria cuneata is extremely variable. On emersed plants, the leaf petioles are often bent toward the ground. Submersed plants often grow from a basal rosette with a long flexuous petiole and a floating sagittate leave. Plants in deep rivers often develop broad, straplike phyllodia.
Emersed or submersed, and vegetatively plastic, with large, edible tubers; lvs long-petioled, sagittate to lanceolate or phyllodial, the blade (when emersed) with lanceolate to deltoid-ovate central lobe 10-18 נ1-10 cm and triangular, pointed, usually much shorter basal lobes, commonly (and unlike all our other spp.) cordate when floating; submersed phyllodia, when present, commonly ribbon-shaped, to 5 dm; scape 1-5+ dm, with 2-10 whorls of fls, occasionally branching at the lowest whorl, the upper fls staminate, the lower pistillate, on ascending pedicels 0.5-2 cm; bracts 1-4 cm, lanceolate, acute or acuminate, whitish and delicate; sep ovate, acuminate, 4-8 mm, reflexed in fr; pet 7-10 mm; stamens 15-25, the filaments subulate, glabrous, about as long as the anthers; achenes 1.8-2.6 mm, with a prominent, rounded wing on the back, the ventral wing nearly or quite as large as the dorsal and confluent with the beak, nearly or quite without facial wings, but with resin- ducts; beak very short, erect, 0.1-0.5 mm; 2n=22. Ponds and marshes, in water or mud (often sandy silt); N.S. and Que. to Mack. and Alas., s. to N.Y., n. O., Ill., Okla., Tex., and Calif. July-Sept. (S. arifolia)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.