7. Arabis crucisetosa Constance & Rollins, Proc. Biol. Soc. Wash. 49: 147. 1936.
Perennials; (caudex usually simple, rarely branched, covered with persistent petiolar remains); sparsely to densely pubescent basally, trichomes short-stalked, cruciform or 3-rayed, stellate, (to 0.4 mm in diam.). Stems simple or few from caudex, erect, unbranched or rarely branched (few) distally, (1-)1.5-4(-5) dm, (glabrous throughout or sparsely pubescent proximally). Basal leaves: petiole 0.5-2.5(-3) cm; blade oblanceolate to obovate, (0.6-)1-3.5(-4.5) cm × (3-)5-15(-20) mm, margins entire or dentate, (not ciliate), apex obtuse, surfaces uniformly pubescent, trichomes short-stalked, stellate. Cauline leaves 3 or 4(-6); blade linear, oblong or oblanceolate, 1-3(-4) cm × (1.5-)3-7(-10) mm, base cuneate, not auriculate, margins usually entire, rarely few-toothed, apex obtuse, surfaces glabrous or sparsely pubescent at least along margin. Racemes simple. Fruiting pedicels ascending to divaricate, (5-)8-20 mm, (glabrous). Flowers: sepals (greenish), oblong, 2.5-4 × 1-1.5 mm, lateral pair saccate basally; petals white, oblanceolate, 7-9 × 2.5-3.5 mm, apex rounded; filaments 2.5-4 mm; anthers oblong, 0.8-1 mm; (gynophore to 0.5 mm). Fruits divaricate, slightly torulose, sometimes slightly curved, slightly flattened, (1.3-)1.7-3.5(-4) cm × 1-1.5 mm; valves each with obscure midvein extending to middle; ovules 14-28 per ovary; style 0.5-1.3 mm. Seeds not winged, oblong, 1-1.2 × 0.5-0.6 mm. 2n = 32.
Flowering Apr-Jun. Open woods, rocky bluffs, steep banks, canyon margins; 400-1800 m; Idaho, Oreg., Wash.
Arabis crucisetosa is known from Idaho, Lewis, and Nez Perce counties in Idaho, from Wallowa County in Oregon, and from Asotin County in Washington.