Arabis constancei Rollins, Contr. Gray Herb. 201: 5, plate 1. 1971; A. suffrutescens S. Watson var. perstylosa Rollins

Perennials; long-lived; sexual; caudex woody. Stems usually 1 per caudex branch, arising from center of rosette, elevated above ground surface on woody base, 1.2-3 dm, glabrous throughout. Basal leaves: blade narrowly oblanceolate, 1.5-4 mm wide, margins entire, ciliate, trichomes (simple, mixed with fewer stalked, 2-rayed), 0.3-0.8 mm, surfaces glabrous. Cauline leaves: 6-12, not concealing stem; blade auricles absent, surfaces of distalmost leaves glabrous. Racemes 5-15-flowered, unbranched. Fruiting pedicels arched, strongly recurved proximally, 4-12 mm, glabrous. Flowers divaricate-ascending at anthesis; sepals glabrous; petals creamy white, 6-8 × 1.5-2 mm, glabrous; pollen ellipsoid. Fruits pendent, not appressed to rachis, usually secund, straight or slightly curved, edges often somewhat undulate (not parallel), 4-7.5 cm × 3-3.5 mm; valves glabrous; ovules 18-28 per ovary; style 2.5-5 mm. Seeds uniseriate, 3-4 × 2.5-3 mm; wing continuous, 0.5-1 mm wide. 2n = 14.

Flowering May. Steep ridges, serpentine slopes; 1200-1900 m; Calif.

Boechera constancei was originally treated as a variety of Arabis (Boechera) suffrutescens; it is easily separated from that species by its non-auriculate cauline leaf blades, longer (6-8 versus 4.5-6 mm) petals that are creamy white (versus purple or rose-tipped), much longer style (2.5-5 versus 0.4-1.2 mm), and exerted anthers. This distinctive sexual diploid is thus far known only from the west slope of the Sierra Nevada in Plumas County.