Boechera crandallii |
Boechera sparsiflora |
|
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Crandall's rockcress |
elegant rockcress, sickle-pod rock-cress, slender rockcress, stretching suncress |
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Habit | Perennials; long-lived; (often cespitose); sexual; caudex somewhat woody. | Biennials or perennials; short-lived; sexual; caudex present or absent. |
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, 3–8 dm, densely pubescent proximally, trichomes simple mixed with fewer short-stalked, 2-rayed ones, 0.4–1.5 mm, glabrous or sparsely 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 oblanceolate or linear-oblanceolate, 3–12 mm wide, margins usually entire, rarely dentate, ciliate proximally, trichomes (usually simple), to 1 mm, surfaces densely pubescent, trichomes short-stalked, 2–5-rayed, 0.3–0.8 mm. |
Cauline leaves | 5–14, not concealing stem; blade auricles 0.1–0.5 mm, surfaces of distalmost leaves pubescent. |
(9–)15–35, often concealing stem proximally; blade auricles 3–10 mm, surfaces of distalmost leaves glabrous, sometimes margins ciliate. |
Racemes | 10–30-flowered, usually unbranched. |
12–50-flowered, usually unbranched. |
Flowers | ascending at anthesis; sepals pubescent; petals usually white, 5–7 × 1–2 mm, glabrous; pollen ellipsoid. |
ascending at anthesis; sepals sparsely pubescent; petals usually lavender to purple, rarely white, 7–13 × 2–5 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | ascending to divaricate-ascending, straight, 5–10 mm, pubescent, trichomes branched. |
usually ascending, rarely almost horizontal, straight or slightly recurved, 3–10(–18) mm, usually pubescent, rarely glabrous, trichomes spreading, usually simple. |
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 ascending, rarely almost horizontal, not appressed to rachis, not secund, usually curved, edges parallel, 5–13 cm × 1.7–2 mm; valves glabrous; ovules 90–170 per ovary; style 0.05–0.3 mm. |
Seeds | uniseriate, 0.8–1 × 0.6–0.9 mm; wing continuous (rarely absent), to 0.1 mm wide. |
uniseriate, 1.5–2 × 1–1.5 mm; wing continuous, 0.1–0.2 mm wide. |
2n | = 14. |
= 14. |
Boechera crandallii |
Boechera sparsiflora |
|
Phenology | Flowering May–Jun. | Flowering Apr–Jun. |
Habitat | Rocky slopes and gravelly soil in sagebrush, mountain shrub, open conifer forests | Rocky slopes, clay hills, sandy soil in sagebrush and mountain shrub communities, meadows, and open conifer forests |
Elevation | 2000-2700 m (6600-8900 ft) | 400-2800 m (1300-9200 ft) |
Distribution |
CO
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CA; ID; NV; OR; UT; WA; BC
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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.) |
As circumscribed by R. C. Rollins (1993), Boechera sparsiflora included six varieties encompassing three sexual diploids and a number of apomictic hybrids. The most distinctive of those elements are recognized here as the separate species B. arcuata, B. atrorubens, B. californica, and B. pauciflora. The narrow circumscription of B. sparsiflora adopted here includes only sexual diploids. It is distinguished from other taxa previously assigned to it by having proximal stems densely pubescent with predominantly simple (some 2-rayed) trichomes to 1.5 mm, usually glabrous distal stems, and ascending fruiting pedicels with spreading, usually simple trichomes (rarely glabrous). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 372. | FNA vol. 7, p. 407. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis crandallii, Arabis stenoloba | Arabis sparsiflora, Arabis arcoidea, Arabis campyloloba, Arabis peramoena, Arabis polytricha, Arabis sparsiflora var. peramoena |
Name authority | (B. L. Robinson) W. A. Weber: Phytologia 51: 369. (1982) | (Nuttall) Dorn: Vasc. Pl. Wyoming ed. 3, 376. (2001) |
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