Boechera atrorubens |
Boechera lincolnensis |
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black-flower rockcress, dark-red-flower rockcress, purple sickle-pod rock-cress, sicklepod rockcress |
Lincoln rockcress |
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Habit | Perennials; usually short-lived; sexual; caudex not woody. | Perennials; long-lived; sexual; caudex 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 1 per caudex branch, arising from center of leaf tuft, elevated above ground surface on woody base, 2–4.2 dm, densely pubescent proximally, trichomes short-stalked, 3–6-rayed, 0.1–0.5 mm, similarly pubescent distally. |
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 linear or linear-oblanceolate, 1–2 mm wide, margins entire, rarely ciliate near petiole base, trichomes (simple), to 1 mm, surfaces densely pubescent, trichomes short-stalked, 3–8-rayed, 0.1–0.4 mm. |
Cauline leaves | 7–25, concealing stem proximally; blade auricles 1–4 mm, surfaces of distalmost leaves glabrous. |
10–25, concealing stem proximally; blade auricles absent or, rarely, to 1 mm, surfaces of distalmost leaves densely pubescent. |
Racemes | 6–20-flowered, usually unbranched. |
7–15-flowered, usually unbranched. |
Flowers | ascending at anthesis; sepals pubescent; petals dark reddish purple (drying indigo), 7–9 × 1.5–2 mm, glabrous; pollen ellipsoid. |
divaricate-ascending at anthesis; sepals pubescent; petals lavender to purple, 10–12 × 2–3 mm, glabrous or sparsely pubescent (occasionally some trichomes abaxially); pollen ellipsoid. |
Fruiting pedicels | ascending, usually straight, 5–10 mm, glabrous or pubescent, trichomes spreading, simple. |
divaricate-ascending, straight to slightly curved proximally, recurved distally, 10–20(–25) mm, pubescent, trichomes appressed, branched. |
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 widely pendent to ascending, rarely horizontal, not appressed to rachis, not secund, straight, edges parallel, (3.2–)4–5.5 cm × 2–2.5 mm; valves pubescent throughout; ovules 86–120 per ovary; style 0.1–0.3 mm. |
Seeds | uniseriate, 1.2–1.7 × 0.9–1.2 mm; wing lateral and distal, 0.1–0.2 mm wide. |
biseriate, 1–1.5 × 0.7–0.9 mm; wing continuous, 0.07–0.12 mm wide. |
2n | = 14. |
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Boechera atrorubens |
Boechera lincolnensis |
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Phenology | Flowering Apr–May. | Flowering Apr–May. |
Habitat | Rocky summits and sandy loam on sagebrush slopes | Rocky slopes and gravelly soil with sagebrush and other shrubs |
Elevation | ca. 600 m (ca. 2000 ft) | 1400-1900 m (4600-6200 ft) |
Distribution |
OR; WA
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CA; NV; UT |
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.) |
Recent studies suggest that Boechera lincolnensis is a distinct species (see M. D. Windham and I. A. Al-Shehbaz 2006 for detailed comparison). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 366. | FNA vol. 7, p. 388. |
Parent taxa | Brassicaceae > tribe Boechereae > Boechera | Brassicaceae > tribe Boechereae > Boechera |
Sibling taxa | ||
Synonyms | Arabis atrorubens, Arabis atriflora, Arabis sparsiflora var. atrorubens | Arabis pulchra var. munciensis, B. pulchra var. munciensis |
Name authority | (Suksdorf ex Greene) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 64. (2006) | Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 71. (2006) |
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