Herbs, forming hemispheric clumps 6-8 dm diam., glabrous or sparsely puberulent. Stems 6-10 dm. Leaves spreading; petioles of proximal leaves 1-2.5 cm; blades of midstem leaves suborbiculate to widely ovate, 3.5-5 × 3-5 cm, base obtuse to cordate, symmetric, apex obtuse to rounded, rarely acute. Involucres: peduncle 4-25 mm; involucres erect or ascending, 13-23 mm; bracts 5, 50% connate, 15-20 mm, apex acute to widely ovate. Flowers 6 per involucre; perianth magenta, funnelform, 1.5-2.5 cm. Fruits light brown, with 10 slender ribs visible when wet, widely obovoid to ellipsoid, 6-7.5 mm, tuberculate, glabrous or very sparsely puberulent, secreting mucilage most abundantly on ribs when wetted.
Flowering late spring. Exposed slopes in canyons; of conservation concern; 400-500 m; Idaho, Oreg.
Mirabilis macfarlanei is in the Center for Plant Conservation´s National Collection of Endangered Plants.