Boechera puberula |
Boechera johnstonii |
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Blue Mountain rockcress, hoary rock-cress, silver rockcress |
Johnston's rockcress |
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Habit | Perennials; short-lived; sexual; caudex not woody. | Perennials; long-lived; (cespitose); sexual; 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, 0.5–2 dm, densely pubescent proximally, trichomes short-stalked, 4–10-rayed, 0.07–0.15 mm, sparsely to densely 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, 1.5–4 mm wide, margins entire, not ciliate, surfaces densely pubescent, trichomes short-stalked, 6–14-rayed, 0.07–0.15 mm. |
Cauline leaves | 7–45(–65), concealing stem proximally; blade auricles absent or 0.7–3 mm, surfaces of distalmost leaves pubescent. |
4–10, often concealing stem proximally; blade auricles absent, surfaces of distalmost leaves densely pubescent. |
Racemes | 10–40(–64)-flowered, usually unbranched. |
10–18-flowered, 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, 9–14 × 2–4 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | pendent, recurved distal to horizontal to ascending base, 4–10 mm, pubescent, trichomes appressed, branched. |
divaricate-ascending, straight, 5–14 mm, pubescent, trichomes appressed, 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. |
divaricate-ascending, not appressed to rachis, not secund, straight, edges parallel, 4–6 cm × 2.5–4 mm; valves glabrous; ovules 26–34 per ovary; style (0.7–)1–2 mm. |
Seeds | uniseriate, 1.4–1.8 × 1–1.4 mm; wing continuous, 0.1–0.3 mm wide. |
uniseriate, 1.9–2.7 × 1.5–2.2 mm; wing continuous, 0.3–0.7 mm wide. |
2n | = 14. |
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Boechera puberula |
Boechera johnstonii |
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Phenology | Flowering Apr–Jul. | Flowering Feb–Mar. |
Habitat | Ledges, rocky slopes, gravelly hillsides in sagebrush, pinyon-juniper, and mountain shrub communities | Rocky areas and gravelly soil in chaparral and oak-pine savannas |
Elevation | 1300-2900 m (4300-9500 ft) | 1300-1700 m (4300-5600 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.) |
Of conservation concern. Boechera johnstonii and B. hirshbergiae are too similar to be considered distinct species. Even with the expanded circumscription, this distinctive sexual species is known only from the area of Cuyamaca Lake (San Diego County) and the San Jacinto Mountains (Riverside County). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 399. | FNA vol. 7, p. 386. |
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 johnstonii, Arabis hirshbergiae, B. hirshbergiae |
Name authority | (Nuttall) Dorn: Brittonia, 55: 3. (2003) | (Munz) Al-Shehbaz: Novon 13: 386. (2003) |
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