Boechera sparsiflora |
Boechera lasiocarpa |
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elegant rockcress, sickle-pod rock-cress, slender rockcress, stretching suncress |
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Habit | Biennials or perennials; short-lived; sexual; caudex present or absent. | Perennials; long-lived; sexual; caudex often woody. |
Stems | 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. |
1 or few per caudex branch, arising from center or margin of rosette, somewhat elevated on woody base or near ground surface, (0.7–)2–3.5 dm, densely pubescent proximally, trichomes short-stalked, 4–8-rayed, 0.05–0.15 mm, moderately to sparsely pubescent distally. |
Basal leaves | 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. |
blade narrowly oblanceolate, 2–5 mm wide, margins entire, not ciliate, surfaces densely pubescent, trichomes short-stalked, 4–8-rayed, 0.05–0.15 mm. |
Cauline leaves | (9–)15–35, often concealing stem proximally; blade auricles 3–10 mm, surfaces of distalmost leaves glabrous, sometimes margins ciliate. |
4–10, often concealing stem proximally; blade auricles absent, surfaces of distalmost leaves sparsely to moderately pubescent. |
Racemes | 12–50-flowered, usually unbranched. |
5–12-flowered, usually unbranched. |
Flowers | ascending at anthesis; sepals sparsely pubescent; petals usually lavender to purple, rarely white, 7–13 × 2–5 mm, glabrous; pollen ellipsoid. |
divaricate at anthesis; sepals pubescent; petals purple to lavender, 6–10 × 1.5–2.5 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | usually ascending, rarely almost horizontal, straight or slightly recurved, 3–10(–18) mm, usually pubescent, rarely glabrous, trichomes spreading, usually simple. |
descending, recurved, 4–14 mm, pubescent, trichomes appressed, branched. |
Fruits | 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. |
pendent, usually not appressed to rachis, rarely secund, straight or curved, 2–5 cm × 1.7–2.2 mm; valves glabrous or pubescent throughout; ovules 26–36 per ovary; style 0.2–0.9 mm. |
Seeds | uniseriate, 1.5–2 × 1–1.5 mm; wing continuous, 0.1–0.2 mm wide. |
uniseriate, 1.5–2 × 1–1.5 mm; wing distal or continuous, 0.1–0.2 mm wide. |
2n | = 14. |
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Boechera sparsiflora |
Boechera lasiocarpa |
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Phenology | Flowering Apr–Jun. | Flowering May–Jun. |
Habitat | Rocky slopes, clay hills, sandy soil in sagebrush and mountain shrub communities, meadows, and open conifer forests | Rocky ridges and slopes with dwarf sagebrush |
Elevation | 400-2800 m (1300-9200 ft) | 1800-2800 m (5900-9200 ft) |
Distribution |
CA; ID; NV; OR; UT; WA; BC
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UT |
Discussion | 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.) |
Boechera lasiocarpa is a sexual species that appears to be restricted to the Bear River Mountains and northern Wasatch Range in north-central Utah. Reports of Arabis (Boechera) lasiocarpa from central Idaho (e.g., R. C. Rollins 1993; N. H. Holmgren 2005b) represent B. rollinsiorum (see M. D. Windham and I. A. Al-Shehbaz 2006 for detailed comparison). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 407. | FNA vol. 7, p. 387. |
Parent taxa | Brassicaceae > tribe Boechereae > Boechera | Brassicaceae > tribe Boechereae > Boechera |
Sibling taxa | ||
Synonyms | Arabis sparsiflora, Arabis arcoidea, Arabis campyloloba, Arabis peramoena, Arabis polytricha, Arabis sparsiflora var. peramoena | Arabis lasiocarpa |
Name authority | (Nuttall) Dorn: Vasc. Pl. Wyoming ed. 3, 376. (2001) | (Rollins) Dorn: Brittonia 55: 3. (2003) |
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