39. Boechera gracilipes (Greene) Dorn, Brittonia 55: 3. 2003; Arabis gracilipes Greene, Pittonia 4: 193. 1900. TYPE: United States, Arizona: Flagstaff, May 1893, N. C. Wilson s.n. (lectotype designated by Rollins (1941: 399), NDG; isolectotype, NDG!).

Arabis arcuata (Nuttall) A. Gray var. longipes S. Watson in A. Gray & S. Wats., Syn. Fl. N. Amer. 1(1): 164. 1895; A. perennans S. Watson var. longipes (S. Watson) Jepson, Fl. Calif. 2: 70. 1936. TYPE: United States, Arizona, Mohave Co., near Fort Mohave, Apr 1884, J. G. Lemmon 4184 (holotype, GH!).

     Plants short-lived perennials or biennials, with or without 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 or (rarely) laterally below sterile shoots, 2.5–8.5 dm, lower parts with adundant simple or spurred trichomes 0.9–1.5 mm, upper parts glabrous. Leaves at stem bases oblanceolate, 5–12 mm wide, shallowly dentate, occasionally ciliate near petiole bases, blade surfaces sparsely to densely pubescent with short- to long-stalked, 2–3-rayed trichomes mostly 0.3–0.6 mm; cauline leaves 30–65, often concealing stem proximally, the uppermost usually glabrous, with auricles 0.8–3.0 mm. Inflorescences mostly unbranched, (12–)15–50-flowered; fruiting pedicels (15–)20–47 mm divaricate-ascending or horizontal, recurved, glabrous. Flowers ascending at anthesis; sepals pubescent; petals white to pale lavender, 6–9 ´ 0.6–1.0 mm, glabrous; ovules 130–210 per fruit. Fruits (2.5–)3.0–7.5 cm ´ 1.5–2.8 mm, widely pendent, not appressed to rachises, not secund, curved, with parallel edges, glabrous; style 0.2–0.5 mm. Seeds biseriate, 1.2–1.4 ´ 0.7–0.9 mm; wing continuous or distal, to 0.2 mm wide.

Flowering: Apr–Jun.

Habitat: basalt, limestone, and sandy soils in ponderosa pine forest and pinyon-juniper woodland.

Elevation: 1750–2300 m.

Distribution: United States (Arizona, Nevada, Utah).

Reproductive mode: sexual diploid.