72. Boechera perennans (S. Watson) W. A. Weber, Phytologia 51: 370. 1982; Arabis perennans S. Watson, Proc. Amer. Acad. Arts 22: 467. 1887; A. arcuata (Nuttall) A. Gray var. perennans (S. Watson) M. E. Jones, Proc. Calif. Acad. Sci. 5: 621. 1895. TYPE: United States, Arizona: Pima Co., Santa Catalina Mts., rocky canyon, 15 Apr 1881, C. G. Pringle s.n. (holotype, GH!; isotypes, MO!, NY!).
Arabis angulata Greene ex Wooton & Standley, Contr. U.S. Natl. Herb. 16: 123. 1913. TYPE: United States, Grant: Mangas Springs, 18 miles NW of silver City, 4770 ft, 9 Apr 1903, O. B. Metcalfe 12 (holotype, US!; isotypes, DS!, E!, GH!, K!, MO!, NDG!, NY!, POM!, RM!, 2US!).
Arabis eremophila Greene, Pittonia 4: 194. 1900. TYPE: United States, Arizona, Peach Springs, 30 Apr 1893, N. C. Wilson s.n. (lectotype designated by Rollins (1941: 397), NDG!; isotypes, NDG!, NY!).
Arabis recondita Greene, Pittonia 4: 194. 1900. TYPE: United States, Arizona, Diamond Creek, 1893, N. C. Wilson s.n. (lectyotype designated by Rollins (1941: 397), NDG!).
Plants long-lived perennials, with woody caudices, lacking crowded, persistent leaf bases; sexual, with ellipsoid pollen. Stems usually 2–5 per caudex branch, often elevated above ground surface on woody bases, arising laterally below sterile shoots or leaf rosettes, (1.5–)2.0–7.0 dm, lower parts with many short-stalked, Y-shaped trichomes 0.2–0.4 mm,, these often mixed 3–5-rayed or (rarely) simple trichomes, upper parts usually glabrous. Leaves at stem bases oblanceolate to obovate, 3–15(–20) mm wide, dentate, ciliate proximally with trichomes to 1.2 mm, blade surfaces moderately to densely pubescent with short-stalked, 3–6-rayed trichomes 0.2–0.4 mm; cauline leaves 4–12(–17), not concealing stem, the uppermost glabrous, with auricles 0.5–3.5 mm. Inflorescences mostly unbranched, 16–35-flowered; fruiting pedicels (6–)10–25 mm, mostly horizontal, straight or slightly recurved, usually glabrous. Flowers ascending at anthesis; sepals pubescent; petals white to purplish, 5–9 ´ 1.0–1.5 mm, occasionally with a few trichomes abaxially; ovules 60–96 per fruit. Fruits (3–)4–7 cm ´ 1.7–2.1 mm, widely pendent, not appressed to rachises, not secund, usually curved, with parallel edges, glabrous; style 0.05–0.40 mm. Seeds uniseriate, 1.1–1.5 ´ 0.9–1.2 mm; wing continuous, 0.1–0.2 mm wide. 2n = 14.
Habitat: rocky slopes and gravelly soil in warm desert, chaparral, and low montane habitats.
Elevation: 250–1700 m.
Distribution: Mexico (Baja California, Chihuahua, Sonora), United States (Arizona, California, Nevada, New Mexico, Texas, Utah).
Reproductive mode: sexual diploid.