Boechera crandallii |
Boechera serpenticola |
|
---|---|---|
Crandall's rockcress |
serpentine rockcress |
|
Habit | Perennials; long-lived; (often cespitose); sexual; caudex somewhat woody. | Perennials; long-lived; (cespitose); sexual; caudex woody. |
Stems | 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. |
usually 1 per caudex branch, arising from center of rosette near ground surface, 0.5–1.8 dm, densely pubescent proximally, trichomes short-stalked, 5–8-rayed, 0.1–0.2, sparsely to moderately pubescent distally. |
Basal leaves | 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. |
blade narrowly oblanceolate, 1–2 mm wide, margins entire, ciliate along petiole, trichomes (branched), to 0.5 mm, surfaces densely pubescent, trichomes short-stalked, 5–8-rayed, 0.1–0.2 mm. |
Cauline leaves | 5–14, not concealing stem; blade auricles 0.1–0.5 mm, surfaces of distalmost leaves pubescent. |
4–14, rarely concealing stem proximally; blade auricles 0.1–0.5 mm, surfaces of distalmost leaves densely pubescent. |
Racemes | 10–30-flowered, usually unbranched. |
10–20-flowered, unbranched. |
Flowers | ascending at anthesis; sepals pubescent; petals usually white, 5–7 × 1–2 mm, glabrous; pollen ellipsoid. |
ascending at anthesis; sepals pubescent; petals purple, 6–8 × 1.5–2.5 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | ascending to divaricate-ascending, straight, 5–10 mm, pubescent, trichomes branched. |
divaricate-descending or horizontal, nearly straight, 3–7 mm, pubescent, trichomes appressed, branched. |
Fruits | 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. |
usually divaricate-descending or horizontal, rarely widely pendent, not appressed to rachis, not secund, straight or slightly curved, edges parallel, 3–4.5 cm × 2.5–3 mm; valves sparsely pubescent to glabrate; ovules 20–24 per ovary; style 1.5–2 mm. |
Seeds | uniseriate, 0.8–1 × 0.6–0.9 mm; wing continuous (rarely absent), to 0.1 mm wide. |
uniseriate, 2–2.5 × 1.5–1.8 mm; wing continuous, to 0.2 mm wide. |
2n | = 14. |
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Boechera crandallii |
Boechera serpenticola |
|
Phenology | Flowering May–Jun. | Flowering Mar–Jun. |
Habitat | Rocky slopes and gravelly soil in sagebrush, mountain shrub, open conifer forests | Serpentine ridges and talus |
Elevation | 2000-2700 m (6600-8900 ft) | ca. 1100 m (ca. 3600 ft) |
Distribution |
CO
|
CA |
Discussion | 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.) |
Boechera serpenticola has been confused with B. subpinnatifida but is easily distinguished by its entire (versus subpinnatifid to dentate) leaves, shorter (6–8 versus 9–14 mm) petals, and longer (1.5–2 versus 0.5–1 mm) styles. It is known only from Shasta and Trinity counties in north-central California. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 372. | FNA vol. 7, p. 406. |
Parent taxa | Brassicaceae > tribe Boechereae > Boechera | Brassicaceae > tribe Boechereae > Boechera |
Sibling taxa | ||
Synonyms | Arabis crandallii, Arabis stenoloba | |
Name authority | (B. L. Robinson) W. A. Weber: Phytologia 51: 369. (1982) | Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 82. (2006) |
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