Boechera paupercula |
Boechera tiehmii |
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boechera paupercula, littleleaf rockcress, small-flower rock-cress, tiny suncress |
Tiehm's Rock cress |
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Habit | Perennials; long-lived; (cespitose); sexual; caudex often woody. | Perennials; long-lived; sexual; caudex woody (covered by persistent leaf bases). |
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 2–5 per caudex branch, arising from margin of rosette near ground surface, 0.8–2(–3) 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, (2–)3–7 mm wide, margins usually entire, rarely denticulate, ciliate, trichomes (simple and short-stalked) 2- or 3-rayed, 0.2–0.4 mm, surfaces glabrous. |
Cauline leaves | 2–6, rarely concealing stem; blade auricles 0 (or 0.2–1.5) mm, surfaces of distalmost leaves glabrous. |
3–5, not concealing stem; blade auricles absent or, rarely, to 0.5 mm, surfaces of distalmost leaves glabrous. |
Racemes | 3–8-flowered, unbranched. |
10–16-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 glabrous; petals white to lavender, 4–5 × 1.2–1.7 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | erect, straight, 3–9 mm, glabrous or sparsely pubescent. |
ascending, straight, 3–7 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. |
ascending, not appressed to rachis, not secund, straight, edges parallel, 1.5–3.7 cm × 1.4–1.7 mm; valves glabrous; ovules 14–22 per ovary; style 0.2–0.6 mm. |
Seeds | usually uniseriate, rarely sub-biseriate, 1.5–2(–2.5) × 1–1.4 mm; wing continuous, 0.3–1 mm wide. |
uniseriate, 1.7–2.2 × 1–1.2 mm; wing absent or distal, 0–0.5 mm wide. |
Boechera paupercula |
Boechera tiehmii |
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Phenology | Flowering Jun–Aug. | Flowering Jun–Aug. |
Habitat | Rock outcrops, talus slopes, gravelly soil in alpine and subalpine habitats | Rock outcrops and gravelly soils in alpine and subalpine habitats |
Elevation | 2400-3400 m (7900-11200 ft) | 3000-3500 m (9800-11500 ft) |
Distribution |
CA; ID; OR; WA; WY
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CA; NV |
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.) |
Of conservation concern. Boechera tiehmii is a sexual species considered by R. C. Rollins (1993) to be related to Arabis (Boechera) davidsonii. It is known only from Mono County, California, and Washoe County, Nevada. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 394. | FNA vol. 7, p. 410. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis paupercula, Arabis lyallii var. nubigena, Arabis microphylla var. nubigena, Arabis nubigena | Arabis tiehmii |
Name authority | (Greene) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 75. (2006) | (Rollins) Al-Shehbaz: Novon 13: 389. (2003) |
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