Boechera paupercula |
Boechera macounii |
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boechera paupercula, littleleaf rockcress, small-flower rock-cress, tiny suncress |
littleleaf suncress, Macoun's suncress, sloppy suncress |
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Habit | Perennials; long-lived; (cespitose); sexual; caudex often woody. | Perennials; usually long-lived; apomictic; caudex often 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. |
1 or several per caudex branch, arising from center or margin of rosette near ground surface, 2–3.6 dm, densely pubescent proximally, trichomes simple and short-stalked, 2-rayed, 0.1–0.8 mm, 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 oblanceolate to linear-oblanceolate, 1–3(–5) mm wide, margins entire or minutely toothed, ciliate proximally, trichomes (simple), to 0.7 mm, surfaces densely pubescent, trichomes short-stalked, 3–6-rayed, 0.07–0.3 mm. |
Cauline leaves | 2–6, rarely concealing stem; blade auricles 0 (or 0.2–1.5) mm, surfaces of distalmost leaves glabrous. |
(5–)9–16, often concealing stem proximally; blade auricles 0.5–1.5 mm, surfaces of distalmost leaves glabrous. |
Racemes | 3–8-flowered, unbranched. |
10–33-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. |
divaricate-ascending at anthesis; sepals pubescent; petals lavender to purple, 4–5 × 0.5–0.8 mm, glabrous; pollen spheroid. |
Fruiting pedicels | erect, straight, 3–9 mm, glabrous or sparsely pubescent. |
divaricate-ascending to horizontal, straight, 5–13(–17) mm, usually densely pubescent, rarely glabrous, trichomes appressed, 2- or 3-rayed. |
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. |
divaricate-ascending to descending, not appressed to rachis, not secund, usually curved, edges parallel, 3.5–6.5 cm × 0.8–1.2 mm; valves glabrous; ovules 56–78 per ovary; style 0.1–0.4 mm. |
Seeds | usually uniseriate, rarely sub-biseriate, 1.5–2(–2.5) × 1–1.4 mm; wing continuous, 0.3–1 mm wide. |
uniseriate, 1–1.2 × 0.7–1 mm; wing often continuous, 0.05–0.15 mm wide. |
Boechera paupercula |
Boechera macounii |
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Phenology | Flowering Jun–Aug. | Flowering May–Jul. |
Habitat | Rock outcrops, talus slopes, gravelly soil in alpine and subalpine habitats | Rocky hillsides in open pinewoods |
Elevation | 2400-3400 m (7900-11200 ft) | 2200-2900 m (7200-9500 ft) |
Distribution |
CA; ID; OR; WA; WY
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ID; MT; WY; BC |
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 macounii is an apomictic species that arose through hybridization between B. collinsii and B. microphylla (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. 389. |
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 macounii, Arabis densicaulis, Arabis microphylla var. macounii |
Name authority | (Greene) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 75. (2006) | (S. Watson) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 267. (2007) |
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