Boechera lemmonii |
Boechera sparsiflora |
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Lemmon's rock-cress, Lemmon's suncress, wind-blown suncress |
elegant rockcress, sickle-pod rock-cress, slender rockcress, stretching suncress |
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Habit | Perennials; long-lived; (somewhat cespitose); sexual or apomictic; caudex woody. | Biennials or perennials; short-lived; sexual; caudex present or absent. |
Stems | usually 1 per caudex branch, arising from center of rosette near ground surface, or arising laterally proximal to sterile shoots, 0.5–2(–2.5) dm, glabrous or sparsely pubescent proximally, trichomes short-stalked, 2–6-rayed, 0.1–0.2 mm, glabrous 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 oblanceolate to obovate, 1.5–5 mm wide, margins usually entire, rarely slightly dentate, ciliate along petiole, surfaces densely to sparsely pubescent, trichomes short-stalked, 3–9-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 | 2–8(–12), not concealing stem; blade auricles absent or 0.1–0.5 mm, surfaces of distalmost leaves glabrous or sparsely pubescent. |
(9–)15–35, often concealing stem proximally; blade auricles 3–10 mm, surfaces of distalmost leaves glabrous, sometimes margins ciliate. |
Racemes | 3–12(–17)-flowered, usually unbranched. |
12–50-flowered, usually unbranched. |
Flowers | divaricate-ascending at anthesis; sepals glabrous or sparsely pubescent; petals purple to lavender, 3.5–6 × 1–1.5 mm; pollen ellipsoid or spheroid. |
ascending at anthesis; sepals sparsely pubescent; petals usually lavender to purple, rarely white, 7–13 × 2–5 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | divaricate-ascending to slightly descending, usually slightly recurved, rarely straight, 2–6 mm, glabrous or sparsely pubescent, trichomes appressed, branched. |
usually ascending, rarely almost horizontal, straight or slightly recurved, 3–10(–18) mm, usually pubescent, rarely glabrous, trichomes spreading, usually simple. |
Fruits | divaricate-ascending to slightly descending, not appressed to rachis, secund, straight or curved, edges parallel, (1.6–) 2–4.4 cm × 1.6–2.3 mm; valves glabrous; ovules 28 40(–44) per ovary; style 0.1–0.2 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, 1.3–2 × 1–1.5 mm; wing continuous, 0.1–0.5 mm wide. |
uniseriate, 1.5–2 × 1–1.5 mm; wing continuous, 0.1–0.2 mm wide. |
2n | = 14. |
= 14. |
Boechera lemmonii |
Boechera sparsiflora |
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Phenology | Flowering Jun–Aug. | Flowering Apr–Jun. |
Habitat | Cliffs, talus slopes, and gravelly soil in alpine and subalpine habitats | Rocky slopes, clay hills, sandy soil in sagebrush and mountain shrub communities, meadows, and open conifer forests |
Elevation | 2100-4400 m (6900-14400 ft) | 400-2800 m (1300-9200 ft) |
Distribution |
AK; CA; CO; ID; MT; NV; OR; UT; WA; WY; AB; BC; YT
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CA; ID; NV; OR; UT; WA; BC
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Discussion | Boechera lemmonii is easily recognized by its combination of secund fruits, mat-forming habit, purplish sepals, and obovate-oblanceolate cauline leaves. Both sexual and apomictic collections are known; further study is needed to determine whether they truly are conspecific. The taxa traditionally treated as Arabis (Boechera) lemmonii vars. depauperata, drepanoloba, and paddoensis are apomictic hybrids here recognized as distinct species (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison). (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. 388. | FNA vol. 7, p. 407. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis lemmonii, Arabis bracteolata, Arabis canescens var. latifolia, Arabis codyi, Arabis egglestonii, Arabis kennedyi, Arabis latifolia, Arabis oreocallis, Arabis polyclada, Arabis semisepulta | Arabis sparsiflora, Arabis arcoidea, Arabis campyloloba, Arabis peramoena, Arabis polytricha, Arabis sparsiflora var. peramoena |
Name authority | (S. Watson) W. A. Weber: Phytologia 51: 370. (1982) | (Nuttall) Dorn: Vasc. Pl. Wyoming ed. 3, 376. (2001) |
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