Stems erect or ascending, 2-3 dm, leafy mostly in proximal 1/2, openly forked distally, spreading-soft hirsute throughout. Leaves usually widely ascending at 60-80°, abruptly reduced below inflorescence; petiole 0-0.9 cm; blade green adaxially, glaucescent abaxially, broadly ovate, ovate-triangular, or round, 4-7 × 3-6 cm, thick, moderately coriaceous, base cordate to round or cuneate, apex obtuse to round, surfaces glabrous or soft hirsute adaxially, soft hirsute abaxially. Inflorescences primarily terminal, few branched, open; peduncle 3-6 mm, spreading-pubescent, sometimes somewhat glandular, crosswalls of hairs pale; involucres grayish green, widely bell-shaped, 4-6 mm in flower, 7-8 mm in fruit, spreading-pubescent, 40-50% connate, lobes ovate. Flowers 3 per involucre; perianth purplish pink, 0.9-1.1 cm. Fruits pale olive brown, narrowly obovoid, 4-5 mm, ± evenly puberulent with hairs 0.1 mm; ribs round, 0.3-0.5 times width of sulci, 0.5 times as wide as high, slightly rugose (more so on side); sulci slightly darker than ribs, slightly rugose.
Flowering late spring-mid summer. Open, calcareous, shaley outcrops; of conservation concern; 1600-1700 m; Colo.
Mirabilis rotundifolia is clearly closely related to Mirabilis albida and may be only a variant.
Mirabilis rotundifolia is in the Center for Plant Conservation´s National Collection of Endangered Plants.