50. Boechera koehleri (T. J. Howell) Al-Shehbaz, Novon 13: 386. 2003; Arabis koehleri T. J. Howell, Fl. Northw. Amer. 1: 44. 1897. TYPE: United States, Oregon, Douglas Co., Cost Mts., along Umpqua River at Roseburg, cliffs, 17 Apr 1887, T. J. Howell s.n. (holotype, ORE!; isotypes, GH!, MO!, NDG!, 4NY!, US!, WTU).
Arabis arbuscula Greene, Leafl. Bot. Observ. Crit. 2: 77. 1910. TYPE: United States, Oregon, Josephine Co., Eight Dollars Mt., 18 Jun 1904, C. V. Piper 5065 (holotype, US!; isotype, GH!).
Arabis koehleri var. stipitata Rollins, Rhodora 43: 426. 1941. TYPE: United States, Oregon, Josephine Co., Near Waldo on Camp Chicago Trail, 19 April 1934, A. Eastwood & J. T. Howell 1695 (holotype, GH!; isotypes, CAS!, GH!).
Plants long-lived perennials, with woody caudices, with many peg-like persistent leaf bases; sexual, with ellipsoid pollen. Stems usually 1 per caudex branch, elevated above ground surface on woody bases, arising from center of basal rosettes, 0.8–4.5 dm, lower parts with stalked, 2–4-rayed trichomes to 0.5 mm, these mixed with simple trichomes to 1 mm, upper parts glabrous. Leaves at stem bases narrowly oblanceolate, 1–3 mm wide, entire, ciliate proximally with simple trichomes to 1 mm, blade surfaces moderately to sparsely pubescent with stalked, 2–4-rayed trichomes 0.1–0.3(–0.5) mm; cauline leaves 3–17(–30), rarely concealing stem, the uppermost glabrous, with auricles 0.5–2.5 mm. Inflorescences mostly unbranched, 6–20(–35)-flowered; fruiting pedicels 10–18 mm, divaricate-ascending to horizontal, straight, glabrous or with few appressed, branched trichomes. Flowers ascending at anthesis; sepals pubescent; petals deep purple to magenta, 8–12 ´ 2.5–4.0 mm, glabrous; ovules 58–94 per fruit. Fruits 5.0–7.5 cm ´ 1.8–2.5 mm, divaricate-ascending to widely pendent, not appressed to rachises, not secund, curved or rarely straight, with parallel edges, glabrous; style 0.05–0.20 mm. Seeds uniseriate, 1.3–1.8 ´ 1.2–1.5 mm; wing continuous, 0.1–0.2 mm wide.
Habitat: serpentine and limestone outcrops.
Elevation: 100–500 m.
Distribution: United States (California, Oregon).
Reproductive mode: sexual diploid.