15. Boechera covillei (Greene) Windham & Al-Shehbaz, Harvard Pap. Bot. 12: 237. 2007.
Arabis covillei Greene, Repert. Spec. Nov. Regni Veg. 5: 243. 1908; A. leibergii Greene
Perennials; long-lived; apomictic; caudex woody. Stems usually 1 per caudex branch, arising from center of rosette near ground surface, 0.5-2.5 dm, glabrous throughout. Basal leaves: blade oblanceolate, 1.5-5 mm wide, margins entire, ciliate proximally, trichomes (simple), to 0.4 mm, and distally, trichomes short-stalked, 2 or 3 (or 4)-rayed, 0.15-0.4 mm, surfaces glabrous. Cauline leaves: 2-7, not concealing stem; blade with auricles 0.2-1 mm, auricles rarely absent, surfaces of distalmost leaves glabrous. Racemes 2-9-flowered, unbranched. Fruiting pedicels ascending to suberect, straight, 6-20 mm, glabrous. Flowers ascending at anthesis; sepals glabrous; petals lavender to purplish, 5-6 × 1-2 mm, glabrous; pollen spheroid. Fruits ascending to suberect, rarely appressed to rachis, not secund, straight, edges slightly undulate (rarely parallel), 3.5-5 cm × 3-5 mm; valves glabrous; ovules 18-30 per ovary; style 0.2-1 mm. Seeds uniseriate, 4-5 × 3-4 mm; wing continuous, 1-1.5 mm wide.
Flowering Jul-Aug. Rocky slopes in alpine meadows and open coniferous forests; 2200-3500 m; Calif., Nev., Oreg.
Morphological evidence suggests that Boechera covillei is an apomictic species that arose through hybridization between B. howellii and B. lyallii (see M. D. Windham and I. A. Al-Shehbaz 2007b for detailed comparison).