Proceedings of the Davenport Academy of Natural Sciences 4: 29. 1883.
Herbs, annual or perennial, to 75 cm; rhizomes absent; stolons present; corms present. Leaves emersed, sessile, phyllodial, linear to lanceolate, flattened, 15–25 (–40) × 1.5–4 cm, or petiole triangular, 15–50 cm, blade linear to elliptic-lanceolate, 4–10 × 0.3–2 cm. Inflorescences racemes, of 3–6 whorls, 1.5 × 4 cm; peduncle 20–60 cm; bracts connate greater than or equal to ¼ total length, ovate, 4–10 mm, nearly scarious, not papillose; fruiting pedicels spreading, cylindric, 0.8–3 cm. Flowers to 0.8 cm diam.; sepals recurved to spreading, not enclosing flower; filaments dilated, exceeding anthers in length, pubescent; pistillate pedicellate, without ring of sterile stamens. Fruiting heads 1.2–2 cm diam.; achenes cuneate-obovoid, abaxially keeled, 2.5–3 × 1.4–1.8 mm, beaked; faces not tuberculate, wings 1, entire, glands absent; beak ascending to horizontal, 0.4–0.7 mm.
Phenology: Flowering summer (Jul–Aug).
Habitat: Sandy margins and bottoms of lakes, ponds, and swamps
Elevation: 100–1000 m
Ont., Ill., Iowa, Mich., Minn., Mo., Nebr., Wis.