Boechera rollei |
Boechera paupercula |
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Rolle's rock-cress |
boechera paupercula, littleleaf rockcress, small-flower rock-cress, tiny suncress |
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Habit | Perennials; long-lived; sexual; caudex woody. | Perennials; long-lived; (cespitose); sexual; caudex often woody. |
Stems | usually 1 per caudex branch, arising from center of rosette, elevated above ground surface on woody base, 1.5–2.5 dm, glabrous throughout. |
usually 1 per caudex branch, arising from center of rosette near ground surface, 0.3–1.5 dm, densely pubescent proximally, trichomes simple and short-stalked, 2–4-rayed, (0.07–)0.1–0.2 mm, glabrous or sparsely pubescent distally. |
Basal leaves | blade oblanceolate, 3–8 mm wide, margins entire, ciliate proximally, trichomes (simple), 0.2–0.7 mm, surfaces glabrous or sparsely pubescent, trichomes short-stalked, 2–4-rayed, 0.2–0.4 mm. |
blade linear-oblanceolate, 1–3(–5) mm wide, margins entire, ciliate proximally, trichomes to 0.4 mm, surfaces densely pubescent, trichomes short-stalked, 2–6-rayed, (0.07–)0.1–0.2 mm. |
Cauline leaves | 6–12, sometimes concealing stem proximally; blade auricles 0.5–2.5 mm, surfaces of distalmost leaves glabrous. |
2–6, rarely concealing stem; blade auricles 0 (or 0.2–1.5) mm, surfaces of distalmost leaves glabrous. |
Racemes | 3–7-flowered, unbranched. |
3–8-flowered, unbranched. |
Flowers | divaricate-ascending at anthesis; sepals glabrous; petals creamy white, 8–11 × 2–2.5 mm, glabrous; pollen ellipsoid. |
erect at anthesis; sepals glabrous or sparsely pubescent; petals lavender to purplish, 4–6(–7) × 1–2 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | strongly curved proximally, 4–6 mm, glabrous. |
erect, straight, 3–9 mm, glabrous or sparsely pubescent. |
Fruits | pendent, not appressed to rachis, not secund, straight to slightly curved, edges undulate (not parallel), 3.5–6 cm × 2.5–3.5 mm; valves glabrous; ovules 14–22 per ovary; style 0.5–1 mm. |
erect, appressed to rachis, not secund, straight, edges parallel, 2.5–5.5 cm × 1.3–1.7(–2) mm; valves glabrous; ovules 24–40 per ovary; style 0.2–1 mm. |
Seeds | uniseriate, 3–4 × 1.5–2 mm; wing distal and proximal, 0.3–0.6 mm wide. |
usually uniseriate, rarely sub-biseriate, 1.5–2(–2.5) × 1–1.4 mm; wing continuous, 0.3–1 mm wide. |
Boechera rollei |
Boechera paupercula |
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Phenology | Flowering Aug. | Flowering Jun–Aug. |
Habitat | Peridotite rocks on sparsely forested slopes | Rock outcrops, talus slopes, gravelly soil in alpine and subalpine habitats |
Elevation | 1600-1800 m (5200-5900 ft) | 2400-3400 m (7900-11200 ft) |
Distribution |
CA |
CA; ID; OR; WA; WY
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Discussion | Boechera rollei is easily distinguished from the habitally similar B. suffrutescens by its longer (8–11 versus 4.5–6 mm) petals, narrower (2.5–3.5 versus 3–6 mm) fruits, and narrower (0.3–0.6 versus 0.8–1.5 mm) seed wings. This distinctive sexual species is known only from the vicinity of the type locality on the divide between the Applegate and Klamath Rivers in Siskiyou County. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Boechera paupercula is usually subsumed under Arabis (Boechera) lyallii but is amply distinct (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. 403. | FNA vol. 7, p. 394. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis rollei | Arabis paupercula, Arabis lyallii var. nubigena, Arabis microphylla var. nubigena, Arabis nubigena |
Name authority | (Rollins) Al-Shehbaz: Novon 13: 389. (2003) | (Greene) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 75. (2006) |
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