Herbs, perennial, to 130 cm; rhizomes absent; stolons present; corms present. Leaves emersed; petiole 5-winged, 19--85 cm; blade sagittate, 3--19 ´ 2.5--11 cm, basal lobes ± equal to remainder of blade. Inflorescences racemes, of 5--12 whorls, emersed, 10--29 ´ 3--5 cm; peduncles 25--105 cm; bracts distinct or if connate, then less than ¼ total length, lanceolate, 7--30 mm, papery, not papillose; fruiting pedicels spreading to ascending, cylindric, 0.3--2.3 cm. Flowers to 3 cm diam.; sepals recurved to spreading, not enclosing flower or fruiting head; filaments cylindric, longer than anthers, glabrous; pistillate pedicellate, without ring of sterile stamens. Fruiting heads 1--2.2 cm diam.; achenes obovoid, without abaxial keel, 2.1--3.2 ´ 1.4--2.3 mm, beaked; faces not tuberculate, wings 0--2, ± entire, glands absent; beak lateral, strongly recurved, 4--17 mm. 2n = 22. Flowering summer--early fall (Jul--Oct). Slightly basic to slightly acidic ponds, lakes, and swamps; 1--300 m; Ala., Ark., Fla., Ga., Ill., Ind., Iowa, Ky., La., Md., Miss., Mo., N.J., N.Y., N.C., Ohio, Pa., S.C., Tenn., Va., W.Va. The name Sagittaria longirostra (Micheli) J. G. Smith has been misapplied to S. australis (J. G. Smith) Small (E. O. Beal et al. 1980).
From Flora of Indiana (1940) by Charles C. Deam
This is a southern species which is known only from Perry County. It is found on muddy shores.
Main portion of the lf-blade deltoid- ovate, relatively blunt, 3-13 נ2.5-10 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)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.