51. Boechera languida (Rollins) Windham & Al-Shehbaz, Harvard Pap. Bot. 12: 244. 2007.
Arabis demissa Greene var. languida Rollins, Rhodora 43: 388. 1941; Boechera demissa (Greene) W. A. Weber var. languida (Rollins) Dorn
Perennials; short- to long-lived; apomictic; caudex usually not, or, rarely, woody. Stems usually 2-5 per caudex branch, arising from margin of rosette near ground surface, or arising laterally proximal to sterile shoots, 1-3 dm, pubescent proximally, trichomes simple, to 1 mm, mixed with short-stalked, 2-rayed ones, 0.15-0.5 mm, glabrous or sparsely pubescent distally. Basal leaves: blade linear-oblanceolate to oblanceolate, 1-5(-9) mm wide, margins entire, ciliate, trichomes (simple), to 1 mm, surfaces densely pubescent, trichomes simple and 2-4-rayed, 0.15-0.5 mm. Cauline leaves: 3-7, not concealing stem; blade auricles 0.5-1.5 mm, surfaces of distalmost leaves sparsely pubescent or glabrous. Racemes 10-20-flowered, usually unbranched. Fruiting pedicels horizontal, slightly to strongly recurved near apex, 3-13 mm, glabrous or, rarely, with simple trichomes. Flowers divaricate-ascending at anthesis; sepals pubescent; petals white to pale lavender, 4-6 × 1.5-2 mm, glabrous; pollen spheroid. Fruits pendent, not appressed to rachis, not secund, straight to slightly curved, edges parallel, 3-4.5 cm × 1.8-2 mm; valves glabrous; ovules 42-70 per ovary; style 0.1-0.3 mm. Seeds sub-biseriate, 1.2-1.5 × 0.8-1 mm; wing absent or distal, 0.05-0.12 mm wide.
Flowering May-Jun. Rocky slopes in sagebrush and pinyon-juniper communities; 1800-2300 m; Wyo.
Boechera languida is an apomictic hybrid that is often subsumed under Arabis demissa (= B. oxylobula). Morphological evidence suggests a closer relationship to B. spatifolia, which probably is one of its parents (see M. D. Windham and I. A. Al-Shehbaz 2007b for detailed comparison).