22. Boechera divaricarpa (A. Nelson) Á. Löve & D. Löve, Bot. Not. 128: 513. 1976; Arabis divaricarpa A. Nelson, Bot. Gaz. 30: 193. 1900. TYPE: United States, Wyoming, Park Co., Yellowstone National Park, stony and sandy banks of Yellowstone Lake, Aug 1899, Aven Nelson & Elias Nelson 6622 (lectotype designated by Hopkins (1937: 132), RM!; isolectotypes, GH!, MO!).
Arabis stokesiae Rydberg, Fl. Rocky Mts. 361, 1062. 1918. TYPE: United States, Utah, Salt Lake Co., Wasatch Mts., Parley’s Canyon, 8 Jun 1901, S. G. Stokes s.n. (holotype, NY!; isotypes, DS!, US!).
Plants short-lived perennials or biennials, with or without 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, (1.5–)3–9 dm, lower parts glabrous or with sessile, 2–4-rayed (a few simple) trichomes to 0.7 mm, upper parts glabrous. Leaves at stem bases oblanceolate, 2–10 mm wide, entire or rarely denticulate, ciliate on petioles with simple trichomes to 0.8 mm, blade surfaces sparsely to densely pubescent with sessile, 2–6-rayed trichomes 0.1–0.4 mm; cauline leaves (10–)15–56, concealing stem proximally, the uppermost glabrous, with auricles 1–5 mm. Inflorescences mostly unbranched, 12–40(–65)-flowered; fruiting pedicels 5–12 mm, divaricate-ascending to horizontal, straight, glabrous. Flowers divaricate-ascending at anthesis; sepals glabrous or with scattered trichomes; petals purple or rarely lavender, 6–9 ´ 1.5–3.0 mm, glabrous; ovules 114–142 per fruit. Fruits (4.5–)5.5–11 cm ´ 1.7–2.5 mm, divaricate-ascending to horizontal, not appressed to rachises, not secund, straight, with parallel edges, glabrous; style 0.05–0.20 mm. Seeds uniseriate to subbiseriate, 1.4–2.0 ´ 1.0–1.5 mm; wing continuous, 0.1–0.2 mm wide. 2n = 21.
Habitat: rock outcrops, talus slopes and gravelly hillsides in sagebrush, mountain shrub, and open conifer forests.
Elevation: 900–2500 m.
Distribution: United States (California, Idaho, Montana, Nevada, Utah, Washington, Wyoming).
Reproductive mode: apomictic triploid.