54. Boechera lignifera (A. Nelson) W. A. Weber, Phytologia. 51: 370. 1982.
Arabis lignifera A. Nelson, Bull. Torrey Bot. Club 26: 123. 1899
Perennials; short- to long-lived; apomictic or sexual; caudex usually woody. Stems usually 2-5 per caudex branch, arising laterally proximal to sterile shoots, often elevated on woody base, 1.2-4(-5) dm, densely pubescent proximally, trichomes short-stalked, 4-7-rayed, 0.1-0.3 mm, sparsely pubescent or glabrous distally. Basal leaves: blade narrowly oblanceolate, 2-5(-8) mm wide, margins entire, rarely ciliate near petiole base, trichomes (simple or spurred), to 1 mm, surfaces densely pubescent, trichomes short-stalked, 3-7-rayed, 0.05-0.3 mm. Cauline leaves: 4-12(-17), rarely concealing stem proximally; blade auricles 0.5-2 mm, surfaces of distalmost leaves sparsely pubescent. Racemes 6-15(-25)-flowered, usually unbranched. Fruiting pedicels slightly descending, gently recurved, 5-16 mm, glabrous or sparsely pubescent, trichomes appressed, branched. Flowers divaricate-ascending at anthesis; sepals pubescent; petals whitish (often aging pale lavender), 5-7 × 1-1.5 mm, glabrous; pollen ellipsoid or spheroid. Fruits widely pendent, not appressed to rachis, not secund, usually curved, edges parallel, 2.5-5.6 cm × 1.2-2 mm; valves glabrous; ovules 48-74 per ovary; style 0.1-0.2 mm. Seeds uniseriate, 1-1.3 × 0.8-1 mm; wing often continuous, 0.1-0.15 mm wide. 2n = 14.
Flowering Apr-May. Rocky slopes and sandy soil in sagebrush and pinyon-juniper woodlands; 1700-2300 m; Ariz., Colo., Idaho, N.Mex., Utah, Wyo.
Boechera lignifera is commonly found on stabilized sand dunes. The related B. cobrensis often is found in similar habitats, and the two species can be difficult to distinguish where their ranges overlap in Idaho and Wyoming. It is possible that B. cobrensis was involved in the origin of some apomictic populations currently assigned to B. lignifera.