Boechera atrorubens |
Boechera nevadensis |
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black-flower rockcress, dark-red-flower rockcress, purple sickle-pod rock-cress, sicklepod rockcress |
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Habit | Perennials; usually short-lived; sexual; caudex not woody. | Perennials; short- to long-lived; sexual; caudex usually not woody. |
Stems | usually 1 per caudex branch, arising from center of rosette near ground surface, 0.8–6 dm, sparsely pubescent proximally, trichomes short-stalked and simple, (scattered), 2-rayed, 0.1–0.15 mm, glabrous distally. |
usually 2–4 per caudex branch, arising from center of rosette near ground surface, or arising laterally proximal to sterile shoots, 0.6–2 dm, glabrous throughout. |
Basal leaves | blade oblanceolate, 4–10 mm wide, margins usually dentate, not ciliate, surfaces densely pubescent, trichomes short-stalked, 3- or 4-rayed, 0.1–0.2 mm. |
blade oblanceolate, 2–6 mm wide, margins entire, rarely ciliate along petiole, trichomes (simple), 0.5–0.7 mm, surfaces glabrous. |
Cauline leaves | 7–25, concealing stem proximally; blade auricles 1–4 mm, surfaces of distalmost leaves glabrous. |
5–9, rarely concealing stem proximally; blade auricles 0.7–2.5 mm, surfaces of distalmost leaves glabrous. |
Racemes | 6–20-flowered, usually unbranched. |
4–12-flowered, usually unbranched. |
Flowers | ascending at anthesis; sepals pubescent; petals dark reddish purple (drying indigo), 7–9 × 1.5–2 mm, glabrous; pollen ellipsoid. |
ascending at anthesis; sepals glabrous; petals lavender, 4–5.5 × 1.5–2 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | ascending, usually straight, 5–10 mm, glabrous or pubescent, trichomes spreading, simple. |
divaricate-ascending to horizontal, straight, 2.5–8 mm, glabrous. |
Fruits | ascending, not appressed to rachis, not secund, curved or straight, edges parallel, (4–)6–12 cm × 1.7–2.2 mm; valves glabrous; ovules 80–100 per ovary; style 0.2–0.5 mm. |
usually divaricate-ascending, rarely slightly descending, usually secund, straight to slightly curved, 1.9–4 cm × 2–3 mm; valves glabrous; ovules 52–72 per ovary; style 0.05–0.2 mm. |
Seeds | uniseriate, 1.2–1.7 × 0.9–1.2 mm; wing lateral and distal, 0.1–0.2 mm wide. |
biseriate, 1.1–1.4 × 0.8–1 mm; wing continuous, 0.07–0.15 mm wide. |
Boechera atrorubens |
Boechera nevadensis |
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Phenology | Flowering Apr–May. | Flowering Jun. |
Habitat | Rocky summits and sandy loam on sagebrush slopes | Ledges and talus of limestone cliffs |
Elevation | ca. 600 m (ca. 2000 ft) | 3000-3400 m (9800-11200 ft) |
Distribution |
OR; WA
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NV |
Discussion | Boechera atrorubens is often treated as a variety of B. sparsiflora (e.g., R. C. Rollins 1993), it is readily separated from that species by having proximal stems sparsely (versus densely) pubescent with much smaller (0.15 versus 1.5 mm) trichomes. The two taxa rarely grow in proximity and, in areas where they are sympatric, B. atrorubens is further distinguished by its narrower (1.5–2 versus 2–5 mm) petals that are dark reddish purple to indigo (versus lavender or white). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Boechera nevadensis usually is treated as a synonym of Arabis pendulina (R. C. Rollins 1993) or B. demissa (N. H. Holmgren 2005b), but is amply distinct from both (see M. D. Windham and I. A. Al-Shehbaz 2006 for detailed comparison). It is known only from Clark and Nye counties. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 366. | FNA vol. 7, p. 391. |
Parent taxa | Brassicaceae > tribe Boechereae > Boechera | Brassicaceae > tribe Boechereae > Boechera |
Sibling taxa | ||
Synonyms | Arabis atrorubens, Arabis atriflora, Arabis sparsiflora var. atrorubens | Arabis nevadensis |
Name authority | (Suksdorf ex Greene) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 64. (2006) | (Tidestrom) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 73. (2006) |
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