Boechera paupercula |
Boechera calderi |
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boechera paupercula, littleleaf rockcress, small-flower rock-cress, tiny suncress |
Calder's rock-cress, Calder's suncress |
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Habit | Perennials; long-lived; (cespitose); sexual; caudex often woody. | Perennials; usually short-lived; apomictic; caudex not 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, 1–4.5 dm, glabrous throughout. |
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 oblanceolate, 1.5–6 mm wide, margins entire, ciliate at petiole base, trichomes to 0.8 mm, surfaces sparsely pubescent, trichomes sessile, malpighiaceous (usually at margin) and 3- or 4-rayed, 0.15–0.4 mm. |
Cauline leaves | 2–6, rarely concealing stem; blade auricles 0 (or 0.2–1.5) mm, surfaces of distalmost leaves glabrous. |
5–17, often concealing stem proximally; blade auricles 1–3 mm, surfaces of distalmost leaves glabrous. |
Racemes | 3–8-flowered, unbranched. |
10–25-flowered, unbranched. |
Flowers | erect at anthesis; sepals glabrous or sparsely pubescent; petals lavender to purplish, 4–6(–7) × 1–2 mm, glabrous; pollen ellipsoid. |
erect at anthesis; sepals glabrous; petals purple, 6–9 × 1.5–2.5 mm, glabrous; pollen spheroid. |
Fruiting pedicels | erect, straight, 3–9 mm, glabrous or sparsely pubescent. |
erect, straight, 5–10 mm, glabrous. |
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. |
erect, appressed to rachis, not secund, straight, edges parallel, 3.5–6.5 cm × 1.8–2.5 mm; valves glabrous; ovules 64–134 per ovary; style 0–0.2 mm. |
Seeds | usually uniseriate, rarely sub-biseriate, 1.5–2(–2.5) × 1–1.4 mm; wing continuous, 0.3–1 mm wide. |
biseriate to sub-biseriate, 1.8–2.2 × 1–1.8 mm; wing continuous, 0.2–0.5 mm wide. |
Boechera paupercula |
Boechera calderi |
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Phenology | Flowering Jun–Aug. | Flowering Jun–Aug. |
Habitat | Rock outcrops, talus slopes, gravelly soil in alpine and subalpine habitats | Exposed rocky ridges, meadows, open forests near timberline |
Elevation | 2400-3400 m (7900-11200 ft) | 1500-3500 m (4900-11500 ft) |
Distribution |
CA; ID; OR; WA; WY
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CA; ID; MT; OR; WA; WY; AB; BC; NT; YT |
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.) |
Morphological evidence suggests that Boechera calderi is an apomictic species that arose through hybridization between B. lyallii and B. stricta (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 394. | FNA vol. 7, p. 368. |
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 calderi |
Name authority | (Greene) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 75. (2006) | (G. A. Mulligan) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 259. (2007) |
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