Sagittaria australis (J.G.Sm.) Small
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Main portion of the lf-blade deltoid- ovate, relatively blunt, 3–13 × 2.5–10 cm, 0.7–2.2 times as long as wide, the basal lobes broad; petiole sharply 5-winged in section; fls in 5–12 whorls; bracts 7–30 mm, equaling or longer than the 7–23 mm pedicels, stramineous, papery-firm, broad-based and long-acuminate; receptacle not markedly echinate; achenes 2.3–3.2 mm, without resin-ducts, usually with 1 wing on each face, these not extending into the beak; beak mostly 0.7–1.7 mm, often ± incurved above the obliquely ascending base; 2n=22; otherwise much like no. 4 [Sagittaria engelmanniana J. G. Sm]. Mostly in circumneutral water of lakes, ponds, or swamps; N.Y., Pa., and N.J. to S.C. and Ga., w. to c. O., s. Ind., se. Mo., and Miss., mainly inland. July–Sept. (S. longirostra, misapplied)