Boechera puberula |
Boechera lignifera |
|
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Blue Mountain rockcress, hoary rock-cress, silver rockcress |
desert rockcress |
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Habit | Perennials; short-lived; sexual; caudex not woody. | Perennials; short- to long-lived; apomictic or sexual; caudex usually 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 laterally proximal to sterile shoots, often elevated on woody base, 1.2–4(–5) dm, densely pubescent proximally, trichomes short-stalked, 4–7-rayed, 0.1–0.3 mm, sparsely pubescent or 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 narrowly oblanceolate, 2–5(–8) mm wide, margins entire, rarely ciliate near petiole base, trichomes (simple or spurred), to 1 mm, surfaces densely pubescent, trichomes short-stalked, 3–7-rayed, 0.05–0.3 mm. |
Cauline leaves | 7–45(–65), concealing stem proximally; blade auricles absent or 0.7–3 mm, surfaces of distalmost leaves pubescent. |
4–12(–17), rarely concealing stem proximally; blade auricles 0.5–2 mm, surfaces of distalmost leaves sparsely pubescent. |
Racemes | 10–40(–64)-flowered, usually unbranched. |
6–15(–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. |
divaricate-ascending at anthesis; sepals pubescent; petals whitish (often aging pale lavender), 5–7 × 1–1.5 mm, glabrous; pollen ellipsoid or spheroid. |
Fruiting pedicels | pendent, recurved distal to horizontal to ascending base, 4–10 mm, pubescent, trichomes appressed, branched. |
slightly descending, gently recurved, 5–16 mm, glabrous or sparsely 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. |
widely pendent, not appressed to rachis, not secund, usually curved, edges parallel, 2.5–5.6 cm × 1.2–2 mm; valves glabrous; ovules 48–74 per ovary; style 0.1–0.2 mm. |
Seeds | uniseriate, 1.4–1.8 × 1–1.4 mm; wing continuous, 0.1–0.3 mm wide. |
uniseriate, 1–1.3 × 0.8–1 mm; wing often continuous, 0.1–0.15 mm wide. |
2n | = 14. |
= 14. |
Boechera puberula |
Boechera lignifera |
|
Phenology | Flowering Apr–Jul. | Flowering Apr–May. |
Habitat | Ledges, rocky slopes, gravelly hillsides in sagebrush, pinyon-juniper, and mountain shrub communities | Rocky slopes and sandy soil in sagebrush and pinyon-juniper woodlands |
Elevation | 1300-2900 m (4300-9500 ft) | 1700-2300 m (5600-7500 ft) |
Distribution |
CA; NV; OR; UT
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AZ; CO; ID; NM; UT; WY
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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.) |
Boechera lignifera is commonly found on stabilized sand dunes. The related B. cobrensis often is found in similar habitats, and the two species can be difficult to distinguish where their ranges overlap in Idaho and Wyoming. It is possible that B. cobrensis was involved in the origin of some apomictic populations currently assigned to B. lignifera. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 399. | FNA vol. 7, p. 388. |
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 lignifera |
Name authority | (Nuttall) Dorn: Brittonia, 55: 3. (2003) | (A. Nelson) W. A. Weber: Phytologia 51: 370. (1982) |
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