Boechera puberula |
Boechera porphyrea |
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Blue Mountain rockcress, hoary rock-cress, silver rockcress |
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Habit | Perennials; short-lived; sexual; caudex not woody. | Perennials; usually long-lived; apomictic; caudex often woody. |
Stems | usually 1 per caudex branch, arising from center of rosette near ground surface, (1–)2–6.3 dm, densely pubescent proximally, trichomes short-stalked, 3–8-rayed, 0.1–0.3(–0.5) mm, similarly pubescent distally. |
1 to several per caudex branch, arising from center of rosette or arising laterally proximal to sterile shoots, somewhat elevated on woody base or from ground surface, 2–5(–9) dm, usually glabrous proximally, rarely sparsely pubescent, trichomes simple and short-stalked, 2- or 3-rayed, 0.1–0.5 mm, glabrous distally. |
Basal leaves | blade oblanceolate to linear-oblanceolate, 1.5–5 mm wide, margins usually dentate, not ciliate, surfaces densely pubescent, trichomes short-stalked, 5–12-rayed, 0.05–0.2 mm. |
blade oblanceolate, (3–)5–15 mm wide, margins dentate, ciliate at least along petiole, trichomes to 1 mm, surfaces pubescent, trichomes short-stalked, 2–6-rayed, 0.1–0.5 mm. |
Cauline leaves | 7–45(–65), concealing stem proximally; blade auricles absent or 0.7–3 mm, surfaces of distalmost leaves pubescent. |
5–17(–21), sometimes concealing stem proximally; blade auricles 0.5–3.5(–5.5) mm, surfaces of distalmost leaves glabrous. |
Racemes | 10–40(–64)-flowered, usually unbranched. |
10–30(–70)-flowered, usually unbranched. |
Flowers | ascending to descending at anthesis; sepals pubescent; petals white to lavender, 5–9 × 0.8–1.8 mm, glabrous; pollen ellipsoid. |
ascending at anthesis; sepals glabrous; petals lavender, 6.5–8.5 × 1–2.5 mm, glabrous; pollen spheroid. |
Fruiting pedicels | pendent, recurved distal to horizontal to ascending base, 4–10 mm, pubescent, trichomes appressed, branched. |
horizontal, gently curved downward, 10–27 mm, glabrous. |
Fruits | closely pendent, rarely appressed to rachis, sometimes somewhat secund, usually straight, edges parallel, 3–6.5 cm × 1.9–2.2 mm; valves pubescent throughout; ovules 38–64 per ovary; style 0.05–0.1 mm. |
widely pendent, not appressed to rachis, not secund, usually curved, edges parallel, 3–7 cm × 1.8–2.5 mm; valves glabrous; ovules 100–160 per ovary; style 0.2–0.5 mm. |
Seeds | uniseriate, 1.4–1.8 × 1–1.4 mm; wing continuous, 0.1–0.3 mm wide. |
sub-biseriate, 1.1–1.6 × 0.9–1.1 mm; wing continuous, 0.1–0.2 mm wide. |
2n | = 14. |
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Boechera puberula |
Boechera porphyrea |
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Phenology | Flowering Apr–Jul. | Flowering late Mar-early May. |
Habitat | Ledges, rocky slopes, gravelly hillsides in sagebrush, pinyon-juniper, and mountain shrub communities | Rocky slopes in evergreen woodlands or desert scrub |
Elevation | 1300-2900 m (4300-9500 ft) | 1200-2100 m (3900-6900 ft) |
Distribution |
CA; NV; OR; UT
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NM; TX |
Discussion | Boechera puberula is a diploid species that appears to intergrade with both B. retrofracta and B. subpinnatifida. The glabrous-fruited specimens discussed by R. C. Rollins (1993) represent apomictic hybrids with other species, primarily B. pendulocarpa. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Morphological evidence suggests that Boechera porphyrea is an apomictic species that arose through hybridization between B. texana and B. perennans (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 399. | FNA vol. 7, p. 398. |
Parent taxa | Brassicaceae > tribe Boechereae > Boechera | Brassicaceae > tribe Boechereae > Boechera |
Sibling taxa | ||
Synonyms | Arabis puberula, Arabis arida, Arabis beckwithii, Arabis lignipes var. impar, Arabis sabulosa, Arabis subpinnatifida var. beckwithii, Arabis subpinnatifida var. impar, B. beckwithii | Arabis porphyrea |
Name authority | (Nuttall) Dorn: Brittonia, 55: 3. (2003) | (Wooton & Standley) Windham: Harvard Pap. Bot. 11: 272. (2007) |
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