Description

Key Characters:

Growth Form: Erect perennial herbs 4–10 dm tall.

Stems: Stems forked, many-branched.

Roots: From a thick root.

Leaves: Leaves simple. Opposite. Blades triangular–ovate to broadly triangular–subcordate, 4–14 cm long, 2–8.5 cm wide., leaf pairs often unequal in size. Apex acute to acuminate. Surfaces glabrous, rarely puberulent. Margins entire or nearly so. Petiolate. Stipules absent.

Flowers: Flowers 1–10 in open or congested, cymose inflorescence, peduncles 1–5 cm long. Involucre with 1 flower, campanulate, deeply 5-lobed, 7–15 mm long. Flowers bisexual (perfect). Perianth variously colored, usually dark purplish red in naturalized forms, wilting in the afternoon, funnelform, 30–50 mm long, tube gradually dilated upward to a broad limb 2–3.5 cm wide, shallowly 5-lobed. Corolla (petals) absent. Stamens 5; filaments distinct or connate at base; anthers didymous, usually exserted. Ovary superior, ellipsoid or globose, closely invested by lower part of perianth; style filiform; stigma capitate, exserted.

Fruit: Anthocarps dark brown to black; obovoid or subglobose; 8–10 mm long; prominently rugose; glabrous or puberulent. Seeds 1 per fruit; closely enclosed by the thin ovary wall.

Ploidy: 2n = 54; 58

Habitat: Dry; disturbed areas.

Elevation Range: 0–610 m.