Boechera puberula |
Boechera peirsonii |
|
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Blue Mountain rockcress, hoary rock-cress, silver rockcress |
Peirson's rockcress, San Bernardino Rock cress |
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Habit | Perennials; short-lived; sexual; caudex not woody. | Perennials; long-lived; (cespitose); apomictic; caudex 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. |
usually 1 per caudex branch, arising from center of rosette near ground surface, 1–2.5 dm, glabrous or sparsely pubescent proximally, trichomes short-stalked, 2–5-rayed (rarely, some simple), 0.4–0.6 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, 2.5–6 mm wide, margins entire, ciliate proximally, trichomes (simple), surfaces densely pubescent, trichomes short-stalked, 4–7-rayed, 0.3–0.5 mm. |
Cauline leaves | 7–45(–65), concealing stem proximally; blade auricles absent or 0.7–3 mm, surfaces of distalmost leaves pubescent. |
3–12, often concealing stem proximally; blade auricles 0.5–2 mm, surfaces of distalmost leaves usually glabrous, sometimes margins ciliate. |
Racemes | 10–40(–64)-flowered, usually unbranched. |
12–25-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 pubescent; petals purple, 5–6 × 1.5–2 mm, glabrous; pollen spheroid. |
Fruiting pedicels | pendent, recurved distal to horizontal to ascending base, 4–10 mm, pubescent, trichomes appressed, branched. |
ascending to divaricate-descending, straight, 2–6 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. |
ascending to divaricate-ascending, not appressed to rachis, not secund, straight, edges parallel, 2–3.7 cm × 2–2.8 mm; valves glabrous; ovules 56–80 per ovary; style 0.1–0.3 mm. |
Seeds | uniseriate, 1.4–1.8 × 1–1.4 mm; wing continuous, 0.1–0.3 mm wide. |
uniseriate, 1–1.5 × 0.8–1 mm; wing distal or continuous, 0.05–0.1 mm wide. |
2n | = 14. |
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Boechera puberula |
Boechera peirsonii |
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Phenology | Flowering Apr–Jul. | Flowering Jun–Sep. |
Habitat | Ledges, rocky slopes, gravelly hillsides in sagebrush, pinyon-juniper, and mountain shrub communities | Granitic ledges and talus slopes |
Elevation | 1300-2900 m (4300-9500 ft) | 2700-3400 m (8900-11200 ft) |
Distribution |
CA; NV; OR; UT
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CA |
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.) |
Boechera peirsonii is an apomictic species of unknown origin; although previously treated as a variety of Arabis (B.) breweri, it is quite distinct from that taxon (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison). All known collections come from the San Bernardino Mountains of southern California, ca. 200 km distant from the nearest populations of B. breweri. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 399. | FNA vol. 7, p. 394. |
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 breweri var. pecuniaria |
Name authority | (Nuttall) Dorn: Brittonia, 55: 3. (2003) | Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 270. (2007) |
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