Fruct. Sem. Pl. 2: 180. 1790.
Plants perennial, 4.5–6(–13) dm; rhizomatous. Stems ribbed, glabrous or strigose. Leaves: ocrea brownish hyaline, cylindric, 10–20 mm, base inflated or not, margins truncate, ciliate with bristles 0.5–4 mm, surface strigose to tomentose; petiole (0.1–)1–2 cm, leaves sometimes sessile; blade 5–17.5 × 2–10 cm, apex acute to acuminate, faces pubescent abaxially, strigose and scabrous adaxially. Inflorescences (50–)100–350 × 7–15 mm; peduncle 10–70 mm, pubescent or glabrous distally; ocreolae not overlapping, margins ciliate with bristles to 3 mm. Pedicels ascending to spreading, 0.5–1 mm. Flowers 1–3 per ocreate fascicle; perianth white, greenish white, or rarely pink, glabrous, accrescent; tepals elliptic to obovate, 2.5–3.5 mm, apex acute to acuminate; filaments distinct, outer ones sometimes adnate to perianth tube; anthers yellow or pink, ovate; styles distinct. Achenes included except for apex and styles, brown to dark brown, biconvex, 3.5–4 × 2–2.8 mm, dull to shiny, smooth to rugose. 2n = 44.
Phenology: Flowering Jul–Oct.
Habitat: Rich deciduous forests, floodplain forests, dry woodlands, thickets
Elevation: 0-500 m
Ont., Que., Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Mass., Mich., Minn., Miss., Mo., Nebr., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Tex., Va., W.Va., Wis., c Mexico.
Tension in the articulation of the pedicels is sufficient to throw mature achenes 3–4 m when the inflorescence is bumped, and the persistent, hooked styles aid in the dispersal of achenes in the fur of animals (H. S. Reed and I. Smoot 1906). A hot infusion of leaves with bark of honey-locust (Gleditsia triacanthos Linnaeus) was used by the Cherokee to treat whooping cough (D. E. Moerman 1998).