Boechera oxylobula |
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Habit | Perennials; short- to long-lived; (cespitose); sexual; caudex usually not woody. |
Stems | usually 3–7 per caudex branch, arising from margin of rosette near ground surface, or arising laterally proximal to sterile shoots, 0.4–2.5 dm, glabrous or pubescent proximally, trichomes simple and short-stalked, 2-rayed, 0.1–0.4 mm, glabrous distally. |
Basal leaves | blade linear to linear-oblanceolate, 1–2.5 mm wide, margins usually entire, rarely denticulate, often ciliate, trichomes (simple), 0.3–0.7 mm, surfaces glabrous or sparsely pubescent, trichomes short-stalked, 2- or 3-rayed, 0.1–0.4 mm. |
Cauline leaves | 3–12, not concealing stem; blade auricles absent, surfaces of distalmost leaves usually glabrous, rarely sparsely pubescent. |
Racemes | 2–12-flowered, unbranched. |
Flowers | ascending-divaricate at anthesis; sepals glabrous or pubescent; petals white to pale lavender, 4–5 × 1.5–2 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | divaricate-ascending to horizontal, slightly to strongly recurved, 3–8 mm, glabrous or sparsely pubescent, trichomes (isolated), simple. |
Fruits | pendent, not appressed to rachis, not or, rarely, weakly secund, straight, edges parallel, 1.5–3.5 cm × 1.2–2 mm; valves glabrous; ovules 28–44 per ovary; style 0.1–0.4 mm. |
Seeds | uniseriate, 0.9–1.2 × 0.6–1 mm; wing often continuous, 0.07–0.1 mm wide. |
Boechera oxylobula |
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Phenology | Flowering May–Jul. |
Habitat | Cliffs, rocky slopes, gravelly soil in sagebrush and open conifer forests |
Elevation | 2100-3600 m (6900-11800 ft) |
Distribution |
CO |
Discussion | Most of the collections assigned here have been called Arabis (Boechera) demissa by other authors (e.g., R. C. Rollins 1993; N. H. Holmgren 2005b). Because the holotype of A. demissa is identical to B. oxylobula in nearly every way (see M. D. Windham and I. A. Al-Shehbaz 2006 for detailed comparison), we treat them as conspecific. Boechera oxylobula is restricted to Garfield, Gunnison, Hinsdale, Lake, Mineral, Park, and Saguache counties in central Colorado. The taxon traditionally treated as A. (Boechera) demissa var. languida is here recognized as an apomictic species of hybrid origin (see Windham and Al-Shehbaz 2007b for detailed comparison). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 391. |
Parent taxa | |
Sibling taxa | |
Synonyms | Arabis oxylobula, Arabis aprica, Arabis demissa, Arabis rugocarpa, B. demissa |
Name authority | (Greene) W. A. Weber: Phytologia 51: 370. (1982) |
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