Flora of the Southeastern United States 45. 1903.
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.
Phenology: Flowering summer–early fall (Jul–Oct).
Habitat: Slightly basic to slightly acidic ponds, lakes, and swamps
Elevation: 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).