in A. Gray et al.,Manual of Botany of the Northern United States (ed. 6) 555. 1890.
Herbs, perennial, to 80 cm; rhizomes absent; stolons present; corms present. Leaves emersed or submersed, sessile, phyllodial, nearly terete; emersed, to 60 × 0.15–0.7 cm; submersed, 3.5–18.5 × 0.15–0.4 cm. Inflorescences racemes, of 1–4 whorls, emersed, 2.5–4 × 2.5–6 cm; peduncles 10–80 cm; bracts connate more than or equal to total length, subulate, 2–3 mm, delicate, not papillose; fruiting pedicels obliquely ascending, filiform, 1 cm. Flowers to 1.5 cm diam.; sepals recurved, not enclosing flower; filaments dilated, equaling anthers, pubescent; pistillate pedicellate, without ring of sterile stamens. Fruiting heads 0.6–1 cm diam.; achenes obovoid-cuneate, abaxially keeled, 2–3 × 1.2–1.5 mm, beaked; faces not tuberculate, wings absent, glands 1–2; beak erect to horizontal, 0.3–0.4 mm. 2n = 22.
Phenology: Flowering summer (Jul–Sep).
Habitat: Sandy pond shores and swamps of acid waters, mainly along Atlantic Coastal Plain
Elevation: 0–100 m
Mass., N.J., N.Y., R.I.