Cynanchum barbigerum (Scheele) Shinners

Stems woody, not corky at base, glabrous. Leaves: 1 stipular col­leter on each side of petiole; peti­ole 1.5–4 mm, glabrous; blade linear, oblong, or lance­olate, 10–45 × 1–18 mm, char­taceous, faintly pinnately veined, base rounded to subcordate, with 1–2 laminar colleters, margins revolute on drying, apex acute to attenuate, mucronulate, surfaces glabrous abaxially, pilosulous on midvein adaxially. Inflorescences umbelliform to shortly racemiform, 3–6-flowered; peduncle 0–0.5 mm. Pedicels 1–3 mm, glabrous. Flowers: calyx lobes ovate, lanceolate, or oblong, apices obtuse to acute, 0.5–1 mm, glabrous, margins scarious, with 1 colleter per sinus; corolla cream to yellowish cream, campanulate, tube 1 mm, lobes erect with spreading and recurved tips, opening not obscured, linear-lanceolate, 2.5–3.5 mm, abaxially glabrous, adaxially densely long-villous marginally and apically with erect, opaque, flattened hairs, densely hispid centrally with downward-pointing acicular translucent hairs; corona segments united to base of column, laminar, acicular, 1–1.5 mm, ± as long as gynostegium; gynostegial column 0.5–0.7 mm; style apex convex. Follicles dark brown, 4–6 × 0.4–0.7 cm, apically acuminate, glabrous. Seeds 10–16, brown, flat to somewhat navicular, 5–6 × 2–3 mm, broadly winged, smooth; coma white, 2–2.5 cm. 2n = 22.

Flowering Mar–Nov; fruiting Apr–Dec. Ridge tops, cliffs, stream banks, edges of marshes, coastal dunes, disturbed areas, limestone, granite, clay, silt or sand soils, thorn scrub, mesquite grasslands, oak woods; 0–800 m; Tex.; Mexico (Coahuila, Nuevo León, Tamaulipas).

Metastelma barbigerum is a morphologically and ecologically variable species. It is the most commonly encountered species of Metastelma in Texas. Plants on the Edwards Plateau are commonly found in more mesic microsites and have much larger leaves than plants found near the coast or in the Rio Grande valley. This name is commonly misapplied to specimens of other species in the southwestern United States and northern Mexico.