Perennials; (caudex simple or branched, covered with persistent petiolar remains); sparsely to moderately pubescent, trichomes sub-setiform, bulbous-based, simple, (to 1.5 mm), often mixed with fewer, forked, stalked ones. Stems simple or few from base (caudex), erect, unbranched, (0.6-)1.5-3.5(-4.5) dm, (sparsely to densely hirsute basally or throughout). Basal leaves: petiole 0.3-1.5 cm, (ciliate); blade oblanceolate to obovate, (0.5-)1-3(-4) cm × (2-)3-6 (-10) mm, margins entire, repand, or obtusely dentate, (ciliate), apex obtuse, surfaces pubescent, trichomes usually simple, sometimes mixed with fewer forked ones, rarely subglabrate. Cauline leaves 3-6 (or 7); blade oblong, 0.4-1(-1.5) cm × (1-)2-4 mm, base not auriculate, margins entire or repand, apex obtuse. Racemes simple, (dense). Fruiting pedicels ascending to suberect, 8-12(-15) mm, (subglabrate or sparsely pubescent). Flowers: sepals (purple), oblong, 4-8 × 1.5-2.5 mm, lateral pair saccate basally; petals purple, spatulate, (9-)10-18(-20) × (2.5-)3.5-6(-8) mm, apex obtuse; filaments 4-9 mm; anthers oblong, 1.5-2 mm. Fruits ascending to suberect, not torulose, sometimes slightly curved, 3.5-6.5 cm × 1.5-2 mm; valves each with prominent midvein extending full length; ovules 24-36 per ovary; style (0.7-)1-2 mm. Seeds narrowly winged nearly throughout except wider distally, oblong, 1.5-2.3 × 1-1.3 mm; wing 0.1-0.3 mm wide. 2n = 32.

Flowering Mar-May(-Jun). Serpentine slopes, rocky hillsides; 200-1800 m; Oreg.

Arabis aculeolata is known only from Curry, Douglas, and Josephine counties.