82. Boechera pusilla (Rollins) Dorn, Vasc. Pl. Wyom. Ed. 3, 376. 2001; Arabis pusilla Rollins, Contr. Gray Herb. 212: 107. 1982. TYPE: United States, Wyoming, Fremont Co., off Wyoming State Hwy. 28, 39 mi. SW of Lander, cracks & crevices of huge metamorphosed rocks, 20 Jun 1981, R. C. & K. W. Rollins 81366 (holotype, GH!; isotypes, BRY!, E!, GH!, MO!, RM!, UC!).
Plants long-lived, cespitose perennials, often with woody caudices, lacking crowded, persistent leaf bases; apomictic, with spheroid pollen. Stems usually 2–6 per caudex branch, arising near ground surface from margin of basal rosettes, 0.5–2.0 dm, lower parts glabrous or with few simple and short-stalked, 2-rayed trichomes to 0.2 mm, upper parts glabrous. Leaves at stem bases linear-oblanceolate, 1–2.5 mm wide, entire, ciliate on petiole with simple trichomes 0.4–0.7 mm, blade surfaces sparsely pubescent with short-stalked, 2–3-rayed trichomes 0.1–0.4 mm or rarely glabrous; cauline leaves 3–5, not concealing stem, the uppermost glabrous or rarely sparsely ciliate, with auricles to 0.2 mm or lacking. Inflorescences unbranched, 6–13-flowered; fruiting pedicels 2–5 mm, horizontal to divaricate-descending, straight or slightly curved downward, glabrous. Flowers divaricate-ascending at anthesis; sepals glabrous or with few spreading, 2-rayed trichomes; petals white to lavender, 4–5 ´ 1.5–1.8 mm, glabrous; ovules 20–32 per fruit. Fruits 1.6–3.2 cm ´ 1.5–2.0 mm, horizontal or divaricate-descending, not appressed to rachises, secund, straight, with parallel edges, glabrous; style 0.1–0.4 mm. Seeds uniseriate, 1.2–1.5 ´ 0.8–0.9 mm; wingless or with distal wing 0.05–0.1 mm wide.
Habitat: cracks and crevices of granitic rock outcrops.
Elevation: 2400–2450 m.
Distribution: United States (Wyoming).
Reproductive mode: apomictic triploid.
Notes: known only from the type collection.