28. Boechera falcatoria (Rollins) Dorn, Brittonia 3: 2003; Arabis falcatoria Rollins, Contr. Gray Herb. 212: 106. 1982. TYPE: United States, Utah, Box Elder Co., in marble chip rock, 3.7 miles north of Grouse Creek, on road to Oakley, Idaho, 9 Jun 1981, Reed C. & Kathryn W. Rollins 81259 (holotype, GH!; isotypes, BRY, MO!, NY!, RM!, RSA!, UC!, US!, UTC).

     Plants short- to long-lived perennials, occasionally with woody caudices, lacking crowded, persistent leaf bases; apomictic, with spheroid pollen. Stems usually 2–7 per caudex branch, arising near ground surface from margin of basal rosettes, 0.5–2(–3) dm, lower parts with abundant, simple and stalked, 2-rayed trichomes 0.3–0.8 mm, upper parts glabrous. Leaves at stem bases narrowly oblanceolate, 1–3 mm wide, entire, ciliate with trichomes to 1 mm, blade surfaces pubescent with stalked, 2–4-rayed trichomes 0.3–0.8 mm; cauline leaves 3–7(–10), not concealing stem, the uppermost glabrous, with auricles 0.2–1 mm. Inflorescences unbranched, 6–15-flowered; fruiting pedicels 3–9 mm, horizontal to divaricate-ascending, straight, glabrous. Flowers ascending at anthesis; sepals pubescent; petals white or lavender, 5–7 ´ 1.5–2.5 mm, glabrous; ovules 50–84 per fruit. Fruits 3.5–6.5 cm ´ 1.7–2.0 mm, horizontal to divaricate-ascending, not appressed to rachises, not secund, usually strongly curved, with parallel edges, glabrous; style 0.05–0.50 mm. Seeds uniseriate, 1.5–2.0 ´ 1.1–1.5 mm; wing continuous, 0.1–0.2 mm wide.

Flowering: May–Jun.

Habitat: rock outcrps and gravelly soil in sagebrush and mountain shrub communities.

Elevation: 2000–2200 m.

Distribution: United States (Utah/Box Elder County).

Reproductive mode: apomictic triploid.