Boechera harrisonii |
Boechera cobrensis |
|
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cobre rock-cress, Masonic rock-cress, sagebrush rockcress |
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Habit | Perennials; long-lived; (some-what cespitose); apomictic; caudex often woody. | Perennials; long-lived; (often cespitose); sexual; caudex somewhat woody (usually without persistent leaf bases). |
Stems | usually 3–7 per caudex branch, arising from margin of rosette near ground surface, 0.5–2.5 dm, usually sparsely pubescent proximally, rarely glabrous, trichomes short-stalked, 2- or 3-rayed, 0.06–0.2 mm, glabrous distally. |
usually 1 per caudex branch, arising from center of rosette near ground surface, (1.2–)2.5–6 dm, densely pubescent proximally, trichomes short-stalked, 4–10-rayed, 0.1–0.2 mm, sparsely pubescent or glabrous distally. |
Basal leaves | blade narrowly oblanceolate, 2–4 mm wide, margins entire or somewhat dentate, ciliate near petiole base, trichomes (simple), to 0.5 mm, surfaces sparsely pubescent, trichomes short-stalked, 2–5-rayed, 0.1–0.25 mm. |
blade linear to narrowly oblanceolate, 1–4 mm wide, margins entire, ciliate near petiole base, trichomes (simple), to 0.6 mm, surfaces densely pubescent, trichomes short-stalked, 4–10-rayed, 0.1–0.2 mm. |
Cauline leaves | 3–7, not concealing stem; blade auricles 0.5–1.5 mm, surfaces of distalmost leaves glabrous. |
5–10, not concealing stem; blade auricles 1–1.5 mm, surfaces of distalmost leaves usually sparsely pubescent. |
Racemes | 5–12-flowered, usually unbranched. |
10–25-flowered, often sparingly branched. |
Flowers | ascending at anthesis; sepals pubescent; petals lavender, 5–7.5 × 0.8–1.5 mm, glabrous; pollen spheroid. |
divaricate-ascending at anthesis; sepals pubescent; petals white to lavender, 3.5–6 × 0.7–1 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | divaricate-ascending, straight, 8–12 mm, glabrous. |
divaricate-ascending to horizontal, often straight proximally, usually strongly recurved or reflexed distally, 4–17 mm, usually pubescent, rarely glabrous, trichomes appressed, branched. |
Fruits | usually divaricate-ascending, rarely nearly horizontal, not appressed to rachis, not secund, curved to straight, edges parallel, 3–4.7 cm × 1–1.5 mm; valves glabrous; ovules 64–86 per ovary; style 0.2–0.5 mm. |
pendent, not appressed to rachis, not secund, straight or slightly curved, edges parallel, 2.5–5.5 cm × 1.7–2.5 mm; valves glabrous; ovules 34–64 per ovary; style 0.05–0.2 mm. |
Seeds | uniseriate, 1.1–1.3 × 0.8–1.1 mm; wing continuous, 0.08–0.1 mm wide. |
uniseriate, 1.4–1.8 × 1–1.2 mm; wing continuous, 0.25–0.5 mm wide. |
2n | = 14. |
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Boechera harrisonii |
Boechera cobrensis |
|
Phenology | Flowering May–Jun. | Flowering May–Jun. |
Habitat | Limestone and quartzite cliffs | Sandy soil, usually under shelter of shrubs in semi-desert communities |
Elevation | 1500-1600 m (4900-5200 ft) | 1200-2800 m (3900-9200 ft) |
Distribution |
UT |
CA; ID; NV; OR; WY
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Discussion | Morphological evidence suggests that Boechera harrisonii is an apomictic species that arose through hybridization between B. microphylla and B. perennans (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison). Boechera harrisonii is known only from Utah and Wasatch counties in north-central Utah. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Boechera cobrensis is a sexual diploid commonly found on stabilized sand dunes. The related B. lignifera often is found in similar habitats, and the two species can be difficult to distinguish where their ranges overlap in Idaho and Wyoming. It is possible that B. cobrensis was involved in the origin of some apomictic populations currently assigned to B. lignifera. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 383. | FNA vol. 7, p. 370. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis harrisonii, B. microphylla var. harrisonii | Arabis cobrensis |
Name authority | (S. L. Welsh) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 266. (2007) | (M. E. Jones) Dorn: Vasc. Pl. Wyoming ed. 3, 375. (2001) |
Web links |