Boechera crandallii |
Boechera covillei |
|
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Crandall's rockcress |
Coville's rock-cress |
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Habit | Perennials; long-lived; (often cespitose); sexual; caudex somewhat woody. | Perennials; long-lived; apomictic; 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, 0.5–2.5 dm, glabrous throughout. |
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 oblanceolate, 1.5–5 mm wide, margins entire, ciliate proximally, trichomes (simple), to 0.4 mm, and distally, trichomes short-stalked, 2 or 3 (or 4)-rayed, 0.15–0.4 mm, surfaces glabrous. |
Cauline leaves | 5–14, not concealing stem; blade auricles 0.1–0.5 mm, surfaces of distalmost leaves pubescent. |
2–7, not concealing stem; blade with auricles 0.2–1 mm, auricles rarely absent, surfaces of distalmost leaves glabrous. |
Racemes | 10–30-flowered, usually unbranched. |
2–9-flowered, unbranched. |
Flowers | ascending at anthesis; sepals pubescent; petals usually white, 5–7 × 1–2 mm, glabrous; pollen ellipsoid. |
ascending at anthesis; sepals glabrous; petals lavender to purplish, 5–6 × 1–2 mm, glabrous; pollen spheroid. |
Fruiting pedicels | ascending to divaricate-ascending, straight, 5–10 mm, pubescent, trichomes branched. |
ascending to suberect, straight, 6–20 mm, glabrous. |
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. |
ascending to suberect, rarely appressed to rachis, not secund, straight, edges slightly undulate (rarely parallel), 3.5–5 cm × 3–5 mm; valves glabrous; ovules 18–30 per ovary; style 0.2–1 mm. |
Seeds | uniseriate, 0.8–1 × 0.6–0.9 mm; wing continuous (rarely absent), to 0.1 mm wide. |
uniseriate, 4–5 × 3–4 mm; wing continuous, 1–1.5 mm wide. |
2n | = 14. |
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Boechera crandallii |
Boechera covillei |
|
Phenology | Flowering May–Jun. | Flowering Jul–Aug. |
Habitat | Rocky slopes and gravelly soil in sagebrush, mountain shrub, open conifer forests | Rocky slopes in alpine meadows and open coniferous forests |
Elevation | 2000-2700 m (6600-8900 ft) | 2200-3500 m (7200-11500 ft) |
Distribution |
CO
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CA; NV; OR |
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.) |
Morphological evidence suggests that Boechera covillei is an apomictic species that arose through hybridization between B. howellii and B. lyallii (see M. D. Windham and I. A. Al-Shehbaz 2007b for detailed comparison). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 372. | FNA vol. 7, p. 371. |
Parent taxa | Brassicaceae > tribe Boechereae > Boechera | Brassicaceae > tribe Boechereae > Boechera |
Sibling taxa | ||
Synonyms | Arabis crandallii, Arabis stenoloba | Arabis covillei, Arabis leibergii |
Name authority | (B. L. Robinson) W. A. Weber: Phytologia 51: 369. (1982) | (Greene) Windham & Al-Shehbaz: Harvard Pap. Bot. 12: 237. (2007) |
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