Boechera quebecensis |
Boechera atrorubens |
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black-flower rockcress, dark-red-flower rockcress, purple sickle-pod rock-cress, sicklepod rockcress |
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Habit | Biennials or perennials; short-lived; apomictic; caudex present or absent. | Perennials; usually short-lived; sexual; caudex not woody. |
Stems | usually 1 per caudex branch, arising from center of rosette near ground surface, 1–4.5 dm, densely pubescent proximally, trichomes sessile, 2–4-rayed, 0.15–0.5 mm, glabrous distally. |
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. |
Basal leaves | blade oblanceolate, 5–15 mm wide, margins denticulate, ciliate proximally, trichomes (simple), to 1 mm, surfaces moderately pubescent, trichomes subsessile, (2- or) 3–7-rayed, 0.1–0.3 mm. |
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. |
Cauline leaves | 4–15, not concealing stem; blade auricles 1–3.5 mm, surfaces of distalmost leaves glabrous. |
7–25, concealing stem proximally; blade auricles 1–4 mm, surfaces of distalmost leaves glabrous. |
Racemes | 11–41-flowered, usually unbranched. |
6–20-flowered, usually unbranched. |
Flowers | divaricate at anthesis; sepals pubescent; petals white, 6–7 × 1–2 mm, glabrous; pollen spheroid. |
ascending at anthesis; sepals pubescent; petals dark reddish purple (drying indigo), 7–9 × 1.5–2 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | horizontal to slightly descending, curved to straight, 3–8(–14) mm, glabrous or with some subappressed, branched trichomes. |
ascending, usually straight, 5–10 mm, glabrous or pubescent, trichomes spreading, simple. |
Fruits | horizontal to slightly descending, not appressed to rachis, secund, straight, edges parallel, 3–6 cm × 1.5–2 mm; valves glabrous; ovules 56–94 per ovary. |
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. |
Seeds | uniseriate, 1.2–1.5 × 1–1.3 mm; wing continuous, 0.1–0.15 mm wide. |
uniseriate, 1.2–1.7 × 0.9–1.2 mm; wing lateral and distal, 0.1–0.2 mm wide. |
Boechera quebecensis |
Boechera atrorubens |
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Phenology | Flowering Jun–Jul. | Flowering Apr–May. |
Habitat | Calcareous rock outcrops and talus slopes | Rocky summits and sandy loam on sagebrush slopes |
Elevation | 0-300 m (0-1000 ft) | ca. 600 m (ca. 2000 ft) |
Distribution |
QC |
OR; WA
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Discussion | Morphological evidence suggests that Boechera quebecensis is an apomictic species that arose through hybridization between B. holboellii and B. stricta; it is most likely to be confused with B. grahamii (see M. D. Windham and I. A. Al-Shehbaz 2007b for detailed comparison). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 7, p. 401. | FNA vol. 7, p. 366. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis divaricarpa var. dechamplainii | Arabis atrorubens, Arabis atriflora, Arabis sparsiflora var. atrorubens |
Name authority | Windham & Al-Shehbaz: Harvard Pap. Bot. 12: 246. (2007) | (Suksdorf ex Greene) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 64. (2006) |
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