Boechera pauciflora |
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Columbia rockcress, few-flower rock-cress, fuzzy suncress, hairy-stem rock-cress, small-flower rockcress |
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Habit | Perennials; short- to long-lived; apomictic; caudex sometimes woody. |
Stems | usually 1 per caudex branch, arising from center of rosette near ground surface, (1.4–)3–11.2 dm, densely pubescent proximally, trichomes simple, 0.6–1.5 mm, mixed with stalked, 2- (or 3-)rayed ones, 0.2–0.4 mm, sparsely pubescent distally. |
Basal leaves | blade oblanceolate, 3–10 mm wide, margins usually dentate, rarely entire, sometimes ciliate, trichomes (simple or branched), to 1 mm, surfaces densely pubescent, trichomes stalked, 2–5-rayed, 0.3–0.6 mm. |
Cauline leaves | (8–)14–60, often concealing stem proximally; blade auricles (1–)3–10 mm, surfaces of distalmost leaves glabrous or sparsely pubescent. |
Racemes | 17–60-flowered, usually unbranched. |
Flowers | divaricate at anthesis; sepals pubescent; petals lavender to whitish, 5–8 × 1–2 mm, glabrous; pollen spheroid. |
Fruiting pedicels | horizontal to divaricate-descending, usually straight, rarely slightly recurved, 4–13 mm, pubescent, trichomes spreading, 2- or 3-rayed. |
Fruits | horizontal, divaricate-descending or widely pendent, not appressed to rachis, not secund, curved, edges parallel, 5.5–10.5 cm × 1.5–2.2 mm; valves glabrous; ovules 80–162 per ovary; style 0.05–0.5 mm. |
Seeds | uniseriate, 1.4–1.8 × 1–1.4 mm; wing continuous, 0.1–0.25 mm wide. |
2n | = 21. |
Boechera pauciflora |
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Phenology | Flowering May–Jun. |
Habitat | Rocky soil in sagebrush areas, mountain shrub communities, edges of conifer forests |
Elevation | 600-2500 m (2000-8200 ft) |
Distribution |
CA; ID; MT; NV; OR; UT; WA; WY; BC
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Discussion | Morphological evidence suggests that Boechera pauciflora is an apomictic species that arose through hybridization between B. retrofracta and B. sparsiflora. Specimens of B. pauciflora are commonly identified as Arabis holboellii var. pinetorum (= B. pinetorum), a superficially similar species restricted to the northern Sierra Nevada and southern Cascade Range (see M. D. Windham and I. A. 2007 for detailed comparison). Arabis elegans A. Nelson (1900), not Tineo & Lojacono (1886) is an illegitimate name, sometimes found in synonymy with Boechera pauciflora. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 393. |
Parent taxa | Brassicaceae > tribe Boechereae > Boechera |
Sibling taxa | |
Synonyms | Sisymbrium pauciflorum, Arabis arcuata var. subvillosa, Arabis columbiana, Arabis perelegans, Arabis sparsiflora var. columbiana, Arabis sparsiflora var. subvillosa, B. sparsiflora var. subvillosa |
Name authority | (Nuttall) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 268. (2007) |
Web links |
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