Tufted twinpod

Perennials; caudex usually simple, rarely branched, (enlarged with persistent leaf bases, cespitose); (silvery) pubescent throughout, trichomes several-rayed, rays typically furcate, (fused at base, arms slender, tuberculate throughout). Stems several from base, decumbent to ascending, (arising laterally beneath a dense rosette), less than 0.1 dm. Basal leaves: (petiole slender); blade (horizontal on the ground), obovate, 0.5-1.5 cm (width 4-8 mm, base tapering abruptly to petiole), margins entire, (apex usually acute, surfaces silvery from a dense incrustation of appressed, stellate trichomes). Cauline leaves: blade oblanceolate, 0.5-1 cm (width 2-3 mm), margins entire, (surfaces densely stellate pubescent). Racemes congested, (subumbellate, often almost sessile, barely exceeding basal leaves). Fruiting pedicels (divaricate, straight), 5-10 mm. Flowers: sepals (yellowish green), narrowly lanceolate, 4-5 mm; petals (erect), oblanceolate, 6-7 mm, (claw weakly differentiated from blade). Fruits didymous, ovate, inflated, 4.8-6 × 6-10 mm, (papery, basal and apical sinuses deep); valves (retaining seeds after dehiscence), pubescent, trichomes loosely spreading; replum obovate, 3-4 mm, as wide as or wider than fruit; ovules 8 per ovary (2-4 abortive); style 4-6 mm. Seeds flattened.

Flowering May-Jun. Calcareous knolls and ridges, clay banks, limey slopes, shaley hills, clay patches; of conservation concern; 1800-2400 m; Wyo.