Cynanchum barbigerum (Scheele) Shinners var. breviflorum Shinners; C. pringlei (A. Gray) Henrickson

Stems woody, not corky at base, minutely puberulent in single line to glabrate. Leaves: 1 stipular colleter on each side of petiole; petiole 1.5–5 mm, sparsely puberulent; blade linear-lanceolate to lanceolate, 7–20 × 3–7 mm, char­taceous, single-veined to faintly pinnate, base cuneate to rounded, with 2 laminar colleters, margins revolute, exaggerated on drying, apex acute to attenuate, mucronulate, surfaces glabrous abaxially, minutely puberulent adaxially on midvein and near margins. Inflorescences umbelliform, 1–4-flowered; peduncle 0–0.5 mm. Pedicels 1.5–2.5 mm, puberulent. Flowers: calyx lobes linear-lanceolate, apices acute to attenuate, 1–1.5 mm, puberulent to glabrate, with 1 colleter per sinus; corolla cream to yellowish cream, campanulate, tube 0.5–1 mm, lobes erect or slightly flared at apex, opening obscured by hairs, lanceolate, 2–3 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, 2–2.5 mm, greater than 2 times as long as gynostegium; gynostegial column subsessile; style apex convex. Follicles dark brown, 4–6 × 0.4–0.5 cm, apically acuminate, glabrous. Seeds 10–16, brown, flat, 5–6 × 2–3 mm, broadly winged, smooth; coma white, 2–2.5 cm.

Flowering May–Oct; fruiting Jun–Oct. Mountain slopes, cliffs, ridgetops, canyons, limestone, granite, rocky soils, desert scrub, thorn scrub, oak woods, grass­lands; 1000–1700 m; Tex.; Mexico.

Metastelma pringlei has the longest corona segments of any Metastelma in the flora area. It is the characteristic representative of the genus in the Chihuahuan Desert portion of the Big Bend region.