67. Boechera pauciflora (Nuttall) Windham & Al-Shehbaz, Harvard Pap. Bot. 11: 268. 2007; Sisymbrium pauciflorum Nuttall in Torrey & A. Gray, Fl. N. Amer. 1: 93. 1838. TYPE: United States, Rocky Mts., T. Nuttall s.n. (holotype, BM!; isotype, PH!).
Arabis arcuata (Nuttall) A. Gray var. subvillosa S. Watson in A. Gray & S. Watson, Syn. Fl. N. Amer. 1(1): 164. 1895; A. sparsiflora Nuttall var. subvillosa (S. Watson) Rollins, Rhodora 43: 403. 1941; Boechera sparsiflora (Nuttall) Dorn var. subvillosa (S. Watson) Dorn, Vasc. Pl. Wyoming, ed. 3. 376. 2001. TYPE: United States, Washington, Whitman Co., Pullman, 20 May 1894, C. V. Piper 1812 (lectotype designated by Rollins (1941: 404), GH!; isotype, US!).
Arabis elegans A. Nelson, Bot. Gaz. 30: 192. 1900, not A. elegans Tineo ex Lojacono, Fl. Sicula 1: 106. 1886; A. perelegans A. Nelson in J. M. Coulter & A. Nelson, New Man. Bot. Centr. Rocky Mts. 228. 1909. TYPE: United States, Wyoming. [Park Co.:] Yellowstone National Park, Undine Falls, partly shaded slopes, 6 Jul 1897, Aven Nelson & Elias Nelson 5676 (lectotype designated by Windham & Al-Shehbaz (2007: 268), RM!; isolectotypes, E!, MO!).
Plants short- to long-lived perennials, occasionally with woody caudices, lacking crowded, persistent leaf bases; apomictic, with spheroid pollen. Stems usually 1 per caudex branch, arising near ground surface from center of basal rosettes, (1.4–)3.0–11.2 dm, lower parts with abundant simple trichomes 0.6–1.5 mm mixed with stalked, 2(or 3)-rayed trichomes 0.2–0.4 mm, upper parts sparsely pubescent. Leaves at stem bases oblanceolate, 3–10 mm wide, dentate or rarely entire, occasionally ciliate with simple or branched trichomes to 1 mm, blade surfaces densely pubescent with stalked, 2–5-rayed trichomes 0.3–0.6 mm; cauline leaves (8–)14–60, often concealing stem proximally, the uppermost glabrous or sparsely pubescent, with auricles (1–)3–10 mm. Inflorescences mostly unbranched, 17–60-flowered; fruiting pedicels 4–13 mm, horizontal to divaricate-descending, straight or rarely slightly recurved, with spreading 2–3-rayed trichomes. Flowers divaricate at anthesis; sepals pubescent; petals lavender to whitish, 5–8 ´ 1–2 mm, glabrous; ovules 80–162 per fruit. Fruits 5.5–10.5 cm ´ 1.5–2.2 mm, horizontal, divaricate-descending or widely pendent, not appressed to rachises, not secund, curved, with parallel edges, glabrous; style 0.05–0.50 mm. Seeds uniseriate, 1.4–1.8 ´ 1.0–1.4 mm; wing continuous, 0.10–0.25 mm wide. 2n = 21.
Habitat: rocky soil in sagebrush areas, mountain shrub communities, and edges of conifer forests. Elevation: 600–2500 m.
Distribution: Canada (British Columbia), United Sates (California, Idaho, Montana, Nevada, Oregon, Utah, Washington, Wyoming).
Reproductive mode: apomictic triploid.