Boechera paupercula |
Boechera pauciflora |
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boechera paupercula, littleleaf rockcress, small-flower rock-cress, tiny suncress |
Columbia rockcress, few-flower rock-cress, fuzzy suncress, hairy-stem rock-cress, small-flower rockcress |
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Habit | Perennials; long-lived; (cespitose); sexual; caudex often woody. | Perennials; short- to long-lived; apomictic; caudex sometimes 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–)3–11.2 dm, densely pubescent proximally, trichomes simple, 0.6–1.5 mm, mixed with stalked, 2- (or 3-)rayed ones, 0.2–0.4 mm, sparsely pubescent 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, 3–10 mm wide, margins usually dentate, rarely entire, sometimes ciliate, trichomes (simple or branched), to 1 mm, surfaces densely pubescent, trichomes stalked, 2–5-rayed, 0.3–0.6 mm. |
Cauline leaves | 2–6, rarely concealing stem; blade auricles 0 (or 0.2–1.5) mm, surfaces of distalmost leaves glabrous. |
(8–)14–60, often concealing stem proximally; blade auricles (1–)3–10 mm, surfaces of distalmost leaves glabrous or sparsely pubescent. |
Racemes | 3–8-flowered, unbranched. |
17–60-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 at anthesis; sepals pubescent; petals lavender to whitish, 5–8 × 1–2 mm, glabrous; pollen spheroid. |
Fruiting pedicels | erect, straight, 3–9 mm, glabrous or sparsely pubescent. |
horizontal to divaricate-descending, usually straight, rarely slightly recurved, 4–13 mm, pubescent, trichomes spreading, 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. |
horizontal, divaricate-descending or widely pendent, not appressed to rachis, not secund, curved, edges parallel, 5.5–10.5 cm × 1.5–2.2 mm; valves glabrous; ovules 80–162 per ovary; style 0.05–0.5 mm. |
Seeds | usually uniseriate, rarely sub-biseriate, 1.5–2(–2.5) × 1–1.4 mm; wing continuous, 0.3–1 mm wide. |
uniseriate, 1.4–1.8 × 1–1.4 mm; wing continuous, 0.1–0.25 mm wide. |
2n | = 21. |
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Boechera paupercula |
Boechera pauciflora |
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Phenology | Flowering Jun–Aug. | Flowering May–Jun. |
Habitat | Rock outcrops, talus slopes, gravelly soil in alpine and subalpine habitats | Rocky soil in sagebrush areas, mountain shrub communities, edges of conifer forests |
Elevation | 2400-3400 m (7900-11200 ft) | 600-2500 m (2000-8200 ft) |
Distribution |
CA; ID; OR; WA; WY
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CA; ID; MT; NV; OR; UT; WA; WY; BC
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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.) |
Morphological evidence suggests that Boechera pauciflora is an apomictic species that arose through hybridization between B. retrofracta and B. sparsiflora. Specimens of B. pauciflora are commonly identified as Arabis holboellii var. pinetorum (= B. pinetorum), a superficially similar species restricted to the northern Sierra Nevada and southern Cascade Range (see M. D. Windham and I. A. 2007 for detailed comparison). Arabis elegans A. Nelson (1900), not Tineo & Lojacono (1886) is an illegitimate name, sometimes found in synonymy with Boechera pauciflora. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 394. | FNA vol. 7, p. 393. |
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 | Sisymbrium pauciflorum, Arabis arcuata var. subvillosa, Arabis columbiana, Arabis perelegans, Arabis sparsiflora var. columbiana, Arabis sparsiflora var. subvillosa, B. sparsiflora var. subvillosa |
Name authority | (Greene) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 75. (2006) | (Nuttall) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 268. (2007) |
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