45. Boechera holboellii (Hornemann) Á. Löve & D. Löve, Bot. Not. 128: 513. 1975; Arabis holboellii Hornemann in Oeder, Fl. Danica 11( Heft 32): 5, pl. 1879. 1827; Erysimum holboellii (Hornem.) Kuntze, Revis. Gen. Pl. 2: 933. 1891. TYPE: Greenland. “In rupibus Insulae Disco ad Jacobshaven,” C. Holböel s.n. (lectotype designated by Windham & Al-Shehbaz (2006: 69), C!; isolectotype, C!).
Arabis holboellii var. tenuis Böcher, Svensk. Bot. Tidskr. 48: 38. 1954; Boechera tenuis (Böcher) Á. Löve & D. Löve, Bot. Not. 128: 513. 1975. TYPE: Greenland, not seen.
Plants short-lived perennials or biennials, with or without caudices, lacking crowded, persistent leaf bases; apomictic (with spheroid pollen) or sexual (with ellipsoid pollen). Stems usually 1 per caudex branch, arising near ground surface from center of basal rosettes, 2–6.7 dm, lower parts with many short-stalked, 4–8-rayed trichomes 0.1–0.3 mm, upper parts glabrous to sparsely pubescent. Leaves at stem bases oblanceolate, 2–5 mm wide, entire, occasionally ciliate near petiole bases with mostly simple trichomes to 0.7 mm, blade surfaces sparsely to moderately pubescent with short-stalked, 4–8-rayed trichomes 0.1–0.3 mm; cauline leaves 7–40, often concealing stem proximally, the uppermost glabrous or sparsely pubescent, with auricles 1–4 mm. Inflorescences mostly unbranched, 10–60-flowered; fruiting pedicels 5–10 mm, descending to reflexed, most abruptly recurved near base, glabrous or with few appressed, branched trichomes. Flowers divaricate to pendent at anthesis; sepals pubescent; petals white, 4–8 ´ 1–2 mm, glabrous; ovules and 80–102 per fruit. Fruits 3.5–6.5 ´ 2.0–2.5 mm, descending to reflexed, not appressed to rachises, strongly secund, often curved, with parallel edges, glabrous. Seeds uniseriate to subbiseriate, 1.4–1.7 ´ 1.0–1.2; wing continuous, to 0.2 mm. 2n = 14, 21.
Habitat: rocky slopes and gravelly soil near coast.
Elevation: 100–300 m.
Reproductive mode: Both sexual diploid and apomictic autotriploid.