49. Boechera johnstonii (Munz) Al-Shehbaz, Novon 13: 386. 2003; Arabis johnstonii Munz, Bull. S. Calif. Acad. Sci. 31: 63. 1932. TYPE: United States, California: Riverside County, San Jacinto Mts., Kenworthy, Thomas Valley, dry rocky slopes, 4500 ft, 19 May 1922, P. A. Munz & I. M. Johnston 5485 (holotype, POM !; isotypes, CAS !, GH !).
Arabis hirshbergiae S. Boyd, Aliso 17: 203. 1998; Boechera hirshbergiae (S. Boyd) Al-Shehbaz, Novon 13: 386. 2003. TYPE: United States, California, San Diego County, Cuyamaca Mts., east of Cuyamaca Reservoir along Sunrise Highway (S-1), 0.5 miles southeast of junction with Hwy 79, about 50 feet north of the road near the Pedro Fages Trail Marker, ca. 33°00'N, 116°30'W, 1400 m, 19 Mar 1995, J. Hirshberg s.n. (holotype, RSA !; Isotype, GH !).
Plants long-lived, cespitose perennials, with woody caudices, lacking crowded, persistent leaf bases; sexual, with ellipsoid pollen. Stems usually 1 per caudex branch, arising near ground surface from center of basal rosettes, 0.5–2 dm, lower parts with abundant short-stalked, 4–10-rayed trichomes 0.07–0.15 mm, upper parts sparsely to densely pubescent. Leaves at stem bases narrowly oblanceolate, 1.5–4.0 mm wide, entire, not ciliate, blade surfaces densely pubescent with short-stalked, 6–14-rayed trichomes 0.07–0.15 mm; cauline leaves 4–10, often concealing stem proximally, the uppermost densely pubescent, lacking auricles. Inflorescences unbranched, 10–18-flowered; fruiting pedicels 5–14 mm, divaricate-ascending, straight, with appressed, branched trichomes. Flowers ascending at anthesis; sepals pubescent; petals purple, 9–14 ´ 2–4 mm, glabrous; ovules 26–34 per fruit. Fruits 4–6 cm ´ 2.5–4.0 mm, divaricate-ascending, not appressed to rachises, not secund, straight, with parallel edges, glabrous; style (0.7–)1.0–2.0 mm. Seeds uniseriate, 1.9–2.7 ´ 1.5–2.2 mm; wing continuous, 0.3–0.7 mm wide.
Habitat: rocky areas and gravelly soil in chaparral and oak-pine savanna.
Elevation: 1300–1700 m.
Distribution: United States (California/ San Diego and Riverside counties).
Reproductive mode: sexual diploid.