J. Arnold Arbor. 25: 175. 1944.
Herbs, stout perennial. Stems 0.3–1.2 m. Leaves: 2–3 pairs near base; petiole 1–8 cm; blade broadly ovate, round, or reniform, 3–12 × 3–14 cm, base cordate, apex rounded, adaxial surface dull green, abaxial surface slightly paler, both surfaces sparsely pubescent with pustulate-based hairs Flowers usually borne singly on branches of inflorescence; perianth 9–10 mm, glabrous, tube yellow-green, limbs pink or rose, lobes sharply reflexed at end of tube; stamens 3, exserted 10–14 mm. Fruits biturbinate, 5–6 × 2.5–3 mm, secreting mucilage when wetted; ribs 10, undulate, narrow; equatorial flange well developed, sinuate.
Phenology: Flowering late spring–early fall.
Habitat: Gypseous shaley clay
Elevation: 800-1200 m
Tex., Mexico (ne Chihuahua)
Of conservation concern.
"thick" is not a number.