25. Boechera elkoensis Windham & Al-Shehbaz, Harvard Pap. Bot. 11: 263. 2007.
Perennials; usually long-lived; apomictic; caudex often woody. Stems 1-5 per caudex branch, arising from center or margin of rosette near ground surface, 1-3 dm, sparsely pubescent proximally, trichomes subsessile, 2-5-rayed, 0.1-0.4 mm, glabrous or sparsely pubescent distally. Basal leaves: blade narrowly oblanceolate, 2-6 mm wide, margins entire, ciliate at petiole base, trichomes (simple), to 0.4 mm, surfaces moderately pubescent, trichomes sessile or subsessile, 2-5-rayed, 0.1-0.4 mm. Cauline leaves: 3-6, not concealing stem; blade auricles absent or 0.2-0.5 mm, surfaces of distalmost leaves glabrous, or sparsely pubescent along margins. Racemes 4-11-flowered, unbranched. Fruiting pedicels erect to ascending, straight, 4-8 mm, usually glabrous, rarely sparsely pubescent, trichomes appressed, branched. Flowers erect to ascending at anthesis; sepals glabrous; petals usually lavender, rarely whitish, 4-7 × 1.2-2 mm, glabrous; pollen spheroid. Fruits erect to ascending, often appressed to rachis, not secund, straight, edges often slightly undulate (not parallel), 3-7 cm × 2-3 mm; valves glabrous; ovules 26-42 per ovary; style 0.05-0.3 mm. Seeds uniseriate, 2.5-3.5 × 1.8-2.5 mm; wing continuous, 0.4-0.9 mm wide.
Flowering Jul. Gravelly soil among rocks in open forests and subalpine meadows; 2000-3200 m; Calif., Nev.
Morphological evidence suggests that Boechera elkoensis is an apomictic species that arose through hybridization between B. platysperma and B. stricta (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison).