63. Boechera oxylobula (Greene) W. A. Weber, Phytologia 51: 370. 1982; Arabis oxylobula Greene, Pittonia 4: 195. 1900. TYPE: United States, Colorado, Garfield County, Glenwood Springs, 18 Jun 1899, G. E. Osterhout s.n. (holotype, NDG!; isotype, RM!).

Arabis aprica Osterhout ex A. Nelson in J. M. Coulter & A. Nelson, New Man. Bot. Centr. Rocky Mts. 228. 1909. TYPE: United States, Colorado, Grand County, Sulphur Springs, on naked limestone slopes, 26 Jun 1907, G. E. Osterhout 3540 (lectotype designated by Rollins (1941: 387), RM!; isolectotypes, BRY!, NY!, RM!).

Arabis demissa Greene, Pl. Baker. 3: 8. 1901; Boechera demissa (Greene) W. A. Weber, Phytologia 51: 370. 1982. TYPE: United States, Colorado, Montrose County, Cimarron, 4 Jun 1901, C. F. Baker 16 (holotype, NDG!).

Arabis rugocarpa Osterhout, Bull. Torrey Bot. Club 31: 357. 1904. TYPE: United States, Colorado, Lake County, at Malta, a station on the Denver and Rio Grande Railway near Leadville, 20 Jun 1903, G. E. Osterhout 2800 (holotype, RM!; isotype, NY!, 2RM!).

     Plants short- to long-lived perennials, with mostly non-woody caudices, lacking crowded, persistent leaf bases; sexual, with ellipsoid pollen. Stems usually 3–7 per caudex branch, arising near ground surface from margin of basal rosettes or laterally below sterile shoot, 0.4–2.5 dm, lower parts glabrous or with simple and short-stalked, 2-rayed trichomes 0.1–0.4 mm, upper parts glabrous. Leaves at stem bases linear to linear-oblanceolate, 1.0–2.5 mm wide, entire or rarely denticulate, often ciliate with simple trichomes 0.3–0.7 mm, blade surfaces glabrous or sparsely pubescent with short-stalked, 2–3-rayed trichomes 0.1–0.4 mm; cauline leaves 3–12, not concealing stem, the uppermost glabrous or rarely sparsely pubescent, without auricles. Inflorescences unbranched, 2–12-flowered; fruiting pedicels 3–8 mm, divaricate-ascending to horizontal, slightly to strongly recurved, glabrous or with isolated simple trichomes. Flowers ascending-divaricate at anthesis; sepals glabrous or pubescent; petals white to pale lavender, 4–5 ´ 1.5–2.0 mm, glabrous; ovules 28–44 per fruit. Fruits 1.5–3.5 cm ´ 1.2–2.0 mm, pendent, not appressed to rachises, rarely weakly secund, straight, with parallel edges, glabrous; style 0.1–0.4 mm. Seeds uniseriate, 0.9–1.2 ´ 0.6–1.0 mm; wing often continuous, 0.07–0.10 mm wide.

Flowering: May–Jul.

Habitat: cliffs, rocky slopes, and gravelly soil in sagebrush and open conifer forest.

Elevation: 2100–3600 m.

Distribution: United States (Colorado).

Reproductive mode: sexual diploid.