99. Boechera spatifolia (Rydberg) Windham & Al-Shehbaz, Harvard Pap. Bot. 11: 84. 2006; Arabis spatifolia Rydberg, Fl. Rocky Mts. 361. 1917; A. fendleri (S. Watson) Greene var. spatifolia (Rydberg) Rollins, Rhodora 43: 394. 1941; Boechera fendleri (S. Wats.) W. A. Weber subsp. spatifolia (Rydberg) W. A. Weber, Phytologia 51: 370. 1982; B. fendleri var. spatifolia (Rydberg) Dorn, Vasc. Pl. Wyoming, ed. 3. 375. 2001. TYPE: United States, Colorado, Larimer Co., Estes Park, 20 Jul 1903, G. E. Osterhout 2808 (holotype, NY!; isotype, RM!).
Plants short- to long-lived perennials, with mostly non-woody caudices, rarely with crowded, persistent leaf bases; sexual, with ellipsoid pollen. Stems usually per caudex branch, arising near ground surface from center of basal rosettes, 1.5–3.5(–5) dm, lower parts many simple and few short-stalked, 2-rayed trichomes 0.3–0.7 mm. Leaves at stem bases narrowly oblanceolate, 1.5–3.0(–4.0) mm wide, entire, strongly ciliate at least on petioles with simple trichomes to 1 mm, blade surfaces glabrous or with few simple and short-stalked, 2-rayed trichomes 0.3–0.7 mm; cauline leaves 5–15(–20), often concealing stem proximally, the uppermost usually glabrous, with auricles 0.5–1.5 mm. Inflorescences mostly unbranched, 10–30-flowered; fruiting pedicels 6–10(–15) mm, horizontal or slightly descending, curved or angled downward, glabrous or rarely with few spreading, simple trichomes. Flowers divaricate-ascending at anthesis; sepals pubescent; petals white or rarely pale lavender, 3.0–3.7(–4.0) ´ 0.5–0.8 mm, glabrous; ovules 90–126 per fruit. Fruits 3.3–5.7 cm ´ 1.2–1.8 mm, pendent, not appressed to rachises, rarely slightly secund, straight or gently curved, with parallel edges, glabrous; style 0.1–0.4 mm. Seeds biseriate, 0.7–0.9 ´ 0.5–0.6 mm; wing distal, 0.05–0.10 mm wide, occasionally absent. 2n = 14.
Habitat: rocky slopes and gravelly soil in sagebrush, pinyon-juniper woodland, open conifer forests and subalpine meadows.
Elevation: 1800–2750 m.
Distribution: United States (Colorado, New Mexico).
Reproductive mode: sexual diploid.