Flora Boreali-Americana 2: 190. 1803.
Herbs, perennial, to 100 cm; rhizomes coarse; stolons absent; corms absent. Leaves submersed or emersed; submersed leaves phyllodial, angled abaxially, flattened adaxially, 6.4–35 × 0.5–4 cm; emersed with petiole triangular, 6.5–17 cm, blade linear to linear-oblanceolate, 2.5–17.4 × 0.2–4 cm. Inflorescences racemes or panicles, of 1–12 whorls, emersed, 2.5–21 × 1–8 cm; peduncles 6.5–29.7 cm; bracts connate more than to equal to ¼ total length, broadly subulate to lanceolate, 20–50 mm, coarse, not papillose; fruiting pedicels spreading, cylindric, 0.5–5 cm. Flowers to 2.3 cm diam.; sepals recurved to spreading, not enclosing flower; filaments dilated, shorter than anthers, pubescent; pistillate flowers pedicellate, without ring of sterile stamens. Fruiting heads 0.6–1.5 cm diam.; achenes oblanceoloid, without abaxial keel, 1.5–2.8 × 1.1–1.5 mm, beaked; faces not tuberculate, abaxial wings 0–1, ± entire, glands 1–2; beak lateral, erect, 0.2 mm.
N.B., N.S., Nfld. and Labr. (Nfld.), Ont., P.E.I., Que., Ala., Ark., Conn., Del., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Mass., Md., Mich., Minn., Miss., Mo., N.C., N.H., N.J., N.Y., Nebr., Ohio, Okla., Pa., R.I., S.C., S.Dak., Tenn., Tex., Va., Vt., W.Va., Wash., Wis., West Indies (Cuba).
Seven varieties of Sagittaria graminea have been recognized, i.e., var. graminea, var. platyphylla Engelmann, var. teres (S. Watson) Bogin, var. weatherbiana Fernald, var. cristata (Engelmann) Bogin, var. chapmanii J. G. Smith, and var. macrocarpa (J. G. Smith) Bogin (C. Bogin 1955). We accept only one infraspecific rank, i.e., subspecies. Consequently, we have made the appropriate combinations. We accept all of the taxa accepted by Bogin at the varietal level. At specific level we accept Bogin’s var. platyphylla, var. teres, and var. cristata and at subspecific level his var. graminea, var. chapmanii, and var. weatherbiana.
Sagittaria graminea var. macrocarpa actually is synonymous with var. graminea (E. O. Beal 1960b). We therefore are following Beal in recognizing var. macrocarpa sensu Bogin as S. fasciculata. We also accept var. platyphylla, var. teres, and var. cristata at the specific level, leaving only three subspecies. These subspecies can be separated by the branching of the inflorescence and the length of pistillate pedicels.
Subspecies 3 (3 in the flora).