Med. Repos., hexade 2, 5: 358. 1808. (as terrestre)
Leaves connate at base, obovate-oblanceolate to spatulate, 1.5–3.9 × 0.8–1.4(–1.5) mm, 2+-veined. Stem and leaf scales present. Inflorescences: bracts absent. Pedicels 0.4–0.6 mm in fruit. Flowers usually solitary or 1 staminate and 1 pistillate opposed by 1 pistillate; styles deflexed; pollen yellow. Schizocarps (0.5–)0.6–0.7(–0.8) × (0.5–)0.8–1 mm, shorter than wide; mericarps black, not swollen, winged only at apex, wings straight, 0.01–0.03 mm wide. 2n = 10.
Phenology: Flowering Apr–Jul(–Aug), Nov–Dec.
Habitat: Seasonally wet hollows, damp soils, cultivated fields, rocky grounds, paths, tracks, sandy bars.
Elevation: 0–600 m.
N.B., Ark., Conn., D.C., Ill., Ind., Kans., Ky., La., Mass., Miss., Mo., N.Y., N.C., N.Dak., Ohio, Pa., Tenn., Tex., Va., Mexico, Central America, South America, introduced in Asia (China, Japan).