18. Boechera davidsonii (Greene) N. H. Holmgren, Intermountain Fl. 2b: 368. 2005; Arabis davidsonii Greene, Leafl. Bot. Observ. Crit. 2: 159. 1911; A. lyallii S. Watson var. davidsonii (Greene) Smiley, Univ. Calif. Publ. Bot. 9: 205. 1921. TYPE: United States, California, Inyo County, moist rocks, below Sabrina Lake, Bishop Creek, 11 Jul 1911, A. Davidson 2728 (holotype, NDG!; isotypes, POM!, UC!).
Arabis brucae M. E. Jones, Contr. W. Bot. 14: 37. 1912. TYPE: United States, California, Hills near Davis Creek, Jun 1898, Mrs. R. M. Austin & Mrs. C. C. Bruce 2251 (lectotype designated by Rollins (1941: 364), POM!)
Arabis cognata Jepson, Man. Fl. Pl. Calif. 429. 1925. TYPE: United States, California, Plumas Co., Mt. Elwell, 7800 ft, 11 Jul 1912, C. M. Wilder s.n. (holotype, JEPS!; isotypes, E!, US!).
Arabis davidsonii var. parva Rollins, Harvard Pap. Bot. 4: 43. 1993. TYPE: United States, California, Tulare Co., 24 air miles ENE of Kernville, crest of ridge S of Chimney Creek Campground, granitic rocks, T24S, R36E, sect. 20, center of E 1/2, ca. 7500 ft, 9 Jun 1986, B. Ertter, B. Holland & V. Dains 6363 (holotype, GH!; isotypes, MO!, UC!).
Plants long-lived, cespitose perennials, with woody caudices, the caudex branches thickly covered by crowded, persistent leaf bases; sexual, with ellipsoid pollen. Stems usually 1 per caudex branch, arising near ground surface from center of basal rosettes, 0.6–2.3 dm, glabrous throughout. Leaves at stem bases oblanceolate, 3.5–14 mm wide, entire or very rarely slightly dentate, not ciliate, blade surfaces glabrous; cauline leaves 3–10, not concealing stem, glabrous, without auricles. Inflorescences mostly unbranched, 4–24-flowered; fruiting pedicels 3–18 mm, ascending, straight, glabrous. Flowers ascending at anthesis; sepals glabrous; petals white to lavender, 6–10 ´ 2.5–4.0 mm, glabrous; ovules 28–50 per fruit. Fruits 2.5–7.0 cm ´ 1.5–2.5 mm, ascending to divaricate-ascending, not appressed to rachises, not secund, straight to slightly curved, with parallel edges, glabrous; style 0.1–0.8 mm. Seeds uniseriate, 1.8–2.2 ´ 0.8–1.7 mm; wing distal or continuous, 0.1–0.5 mm wide.
Habitat: ledges and crevices of rock outcrops.
Elevation: 1200–3400 m.
Distribution: United States (California, Nevada, Oregon).
Reproductive mode: sexual diploid.