Boechera paupercula |
Boechera cusickii |
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boechera paupercula, littleleaf rockcress, small-flower rock-cress, tiny suncress |
Cusick's rock-cress |
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Habit | Perennials; long-lived; (cespitose); sexual; caudex often woody. | Perennials; long-lived; (often cespitose); sexual; caudex usually woody. |
Stems | 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. |
usually 1 per caudex branch, arising from center of rosette near ground surface, 1–2.5(–3.8) dm, densely pubescent proximally, trichomes simple, 0.5–1.5 mm, sparsely pubescent or glabrous distally. |
Basal leaves | 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. |
blade linear to narrowly oblanceolate, 0.5–2 mm wide, margins entire, ciliate, trichomes (simple), 1–1.7 mm, surfaces moderately pubescent, trichomes simple and long-stalked, 2-rayed, 0.5–1.7 mm. |
Cauline leaves | 2–6, rarely concealing stem; blade auricles 0 (or 0.2–1.5) mm, surfaces of distalmost leaves glabrous. |
10–30, often concealing stem proximally; blade auricles 0–0.5 mm, surfaces of distalmost leaves sparsely pubescent. |
Racemes | 3–8-flowered, unbranched. |
5–14-flowered, usually unbranched. |
Flowers | erect at anthesis; sepals glabrous or sparsely pubescent; petals lavender to purplish, 4–6(–7) × 1–2 mm, glabrous; pollen ellipsoid. |
ascending at anthesis; sepals pubescent; petals white to lavender, 6–10 × 2–3 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | erect, straight, 3–9 mm, glabrous or sparsely pubescent. |
ascending, straight, 4–15(–20) mm, glabrous or sparsely pubescent, trichomes simple. |
Fruits | 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. |
ascending to divaricate-ascending, not appressed to rachis, not secund, straight or curved, edges parallel, 4–8(–9.5) cm × 2.3–3 mm; valves glabrous; ovules 56–106 per ovary; style 0.1–0.5 mm. |
Seeds | usually uniseriate, rarely sub-biseriate, 1.5–2(–2.5) × 1–1.4 mm; wing continuous, 0.3–1 mm wide. |
uniseriate, 1.5–2.5 × 1.5–2 mm; wing continuous, 0.1–0.2 mm wide distally. |
Boechera paupercula |
Boechera cusickii |
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Phenology | Flowering Jun–Aug. | Flowering Apr-mid May. |
Habitat | Rock outcrops, talus slopes, gravelly soil in alpine and subalpine habitats | Basaltic bluffs, rocky slopes, rock crevices, gravelly hillsides, sagebrush hills, outcrops of volcanic rock |
Elevation | 2400-3400 m (7900-11200 ft) | 600-1800 m (2000-5900 ft) |
Distribution |
CA; ID; OR; WA; WY
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ID; NV; OR; WA
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Discussion | 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.) |
Peripheral populations of Boechera cusickii in south-central Idaho and northern Nevada have a higher proportion of branched hairs, possibly resulting from hybridization with B. sparsiflora. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 394. | FNA vol. 7, p. 372. |
Parent taxa | Brassicaceae > tribe Boechereae > Boechera | Brassicaceae > tribe Boechereae > Boechera |
Sibling taxa | ||
Synonyms | Arabis paupercula, Arabis lyallii var. nubigena, Arabis microphylla var. nubigena, Arabis nubigena | Arabis cusickii |
Name authority | (Greene) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 75. (2006) | (S. Watson) Al-Shehbaz: Novon 13: 384. (2003) |
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