Boechera puberula |
Boechera crandallii |
|
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Blue Mountain rockcress, hoary rock-cress, silver rockcress |
Crandall's rockcress |
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Habit | Perennials; short-lived; sexual; caudex not woody. | Perennials; long-lived; (often cespitose); sexual; caudex somewhat 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 2–5 per caudex branch, arising from margin of rosette near ground surface, (1–)1.5–4 dm, densely pubescent proximally, trichomes short-stalked, 5–8-rayed, 0.1–0.2 mm, moderately to sparsely pubescent 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 narrowly oblanceolate, 1.5–3(–5) mm wide, margins entire, ciliate along petiole base, trichomes (simple), to 0.6 mm, surfaces densely pubescent, trichomes short-stalked, 5–8-rayed 0.1–0.2 mm. |
Cauline leaves | 7–45(–65), concealing stem proximally; blade auricles absent or 0.7–3 mm, surfaces of distalmost leaves pubescent. |
5–14, not concealing stem; blade auricles 0.1–0.5 mm, surfaces of distalmost leaves pubescent. |
Racemes | 10–40(–64)-flowered, usually unbranched. |
10–30-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 usually white, 5–7 × 1–2 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | pendent, recurved distal to horizontal to ascending base, 4–10 mm, pubescent, trichomes appressed, branched. |
ascending to divaricate-ascending, straight, 5–10 mm, pubescent, trichomes branched. |
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, 3–5.5 cm × 0.9–1.2 mm; valves glabrous; ovules 56–84 per ovary; style 0.1–0.5 mm. |
Seeds | uniseriate, 1.4–1.8 × 1–1.4 mm; wing continuous, 0.1–0.3 mm wide. |
uniseriate, 0.8–1 × 0.6–0.9 mm; wing continuous (rarely absent), to 0.1 mm wide. |
2n | = 14. |
= 14. |
Boechera puberula |
Boechera crandallii |
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Phenology | Flowering Apr–Jul. | Flowering May–Jun. |
Habitat | Ledges, rocky slopes, gravelly hillsides in sagebrush, pinyon-juniper, and mountain shrub communities | Rocky slopes and gravelly soil in sagebrush, mountain shrub, open conifer forests |
Elevation | 1300-2900 m (4300-9500 ft) | 2000-2700 m (6600-8900 ft) |
Distribution |
CA; NV; OR; UT
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CO
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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.) |
Of conservation concern. Boechera crandallii is a sexual diploid known only from the Gunnison Basin of west-central Colorado. Despite its narrow range, the species appears to hybridize frequently, most notably with B. pallidifolia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 399. | FNA vol. 7, p. 372. |
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 crandallii, Arabis stenoloba |
Name authority | (Nuttall) Dorn: Brittonia, 55: 3. (2003) | (B. L. Robinson) W. A. Weber: Phytologia 51: 369. (1982) |
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