Alisma subulatum Linnaeus, Sp. Pl. 1: 343. 1753 (as subulata); Sagittaria lorata (Chapman) Small; S. subulata var. natans (Michaux) J. G. Smith

Herbs, perennial, to 40 cm, on tidal muds; rhizomes absent; stolons present; corms present. Leaves submersed, phyllodial, lenticular, 5--40 ´ 0.1--0.4 cm, or rarely floating; petiole terete, 2.4--4 cm; blade linear-lanceolate to ovate, 1--2.5 ´ 0.3--1.5 cm. Inflorescences racemes, of 2--7 whorls, floating, 2--11 ´ 1.5--4.5 cm; peduncles 5--40 cm; bracts connate more than ¼ total length, subulate, 1.5--4.2 mm, delicate, not papillose; fruiting pedicels recurved, cylindric to club-shaped, 0.2--1.1 cm. Flowers 0.4--1.2 cm diam.; sepals spreading to recurved in staminate, erect in pistillate, enclosing flower or fruiting head; filaments dilated, longer than anther, glabrous; pistillate pedicellate, occasionally with ring of sterile stamens. Fruiting heads 0.55--0.8 cm diam.; achenes oblanceoloid, abaxially keeled, 2 ´ 1.5 mm, beaked; faces not tuberculate, wings 1--2, crenate, glands 0--1; beak lateral, erect, 0.2--0.4 mm. 2n = 22.

Flowering summer--fall. Streams and brackish bays; 0--100 m; Ala., Conn., Del., D.C., Fla., Ga., Md., Mass., Miss., N.J., N.Y., N.C., Pa., R.I., S.C., Va.; South America (Colombia).

Sagittaria subulata occurs in shallow brackish waters near the coast. The plants are especially common in areas that are exposed during low tides.