88. Boechera rigidissima (Rollins) Al-Shehbaz, Novon 13: 389. 2003; Arabis rigidissima Rollins, Rhodora 43: 380. 1941. TYPE: United States, California, Trinity Co., Mary Blaine Mt., gravelly or rocky soil, 6400 ft., 3 Aug 1935, J. P. Tracy 14469 (holotype, GH!; isotype, DS!).

Arabis rigidissima Rollins var. demota Rollins. TYPE: United States, Nevada, Washoe Co., Siera Nevadas, Carson Range, Galena Creek, 1.5 air miles ESE of Mt. Rose Peak, T17N, R19E, sec. 18, 7900 ft, 26 Aug 1982, A. Tiehm 7572 (holotype, GH!; isotypes, CAS!, MO!, NY!, ORE!, RSA!, WS!).

     Plants long-lived perennials, with woody caudices, lacking crowded, persistent leaf bases; apomictic, with spheroid pollen. Stems usually1 per caudex branch, slightly elevated on woody bases or produced near ground surface, arising from center of basal rosettes, 2–6 dm, lower parts with subsessile, 2–3-rayed (rarely simple) trichomes 0.25–0.40 mm, upper parts glabrous. Leaves at stem bases oblanceolate, 2–6 mm wide, entire, ciliate proximally with trichomes to 0.7 mm, blade surfaces sparsely pubescent with subsessile to short-stalked, 2–5-rayed trichomes 0.1–0.4 mm; cauline leaves 5–10, rarely concealing stem proximally, the uppermost glabrous, with auricles 0.5–2 mm. Inflorescences mostly unbranched, 5–16-flowered; fruiting pedicels 4–10 mm, divaricate-ascending, straight, glabrous. Flowers ascending at anthesis; sepals glabrous; petals purple, 6–8 ´ 1.5–2.0 mm, glabrous; ovules 24–54 per fruit. Fruits 4.0–6.5(–7.6) cm ´ 2.5–3.5 mm, divaricate-ascending, not appressed to rachises, not secund, straight, with somewhat undulate (non-parallel) edges, glabrous; style 0.2–0.8 mm. Seeds uniseriate, 2.5–3.2 ´ 1.8–2.5 mm; wing distal, 0.3–1.0 mm wide.

Flowering: Jul–Aug.

Habitat: rocky places in open conifer forest.

Elevation: 1800–1950 m.

Distribtution: United States (California, Nevada).

Reproductive mode: apomictic triploid.