Boechera paupercula |
Boechera cascadensis |
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boechera paupercula, littleleaf rockcress, small-flower rock-cress, tiny suncress |
Cascade rock-cress, Cascade suncress, Cascades rockcress, littleleaf rockcress |
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Habit | Perennials; long-lived; (cespitose); sexual; caudex often woody. | Perennials; long-lived; (cespitose); apomictic; caudex somewhat 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, 0.5–2.2 dm, sparsely pubescent proximally, trichomes simple and short-stalked, 2- or 3-rayed, 0.1–0.2 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 linear-oblanceolate, 0.7–2 mm wide, margins entire, ciliate proximally, trichomes to 0.4 mm, surfaces densely pubescent, trichomes short-stalked, (2- or) 3–6-rayed, 0.05–0.2(–0.3) mm. |
Cauline leaves | 2–6, rarely concealing stem; blade auricles 0 (or 0.2–1.5) mm, surfaces of distalmost leaves glabrous. |
4–6, not concealing stem; blade auricles 0.5–1 mm, surfaces of distalmost leaves glabrous. |
Racemes | 3–8-flowered, unbranched. |
3–11-flowered, 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 or sparsely pubescent; petals lavender, 5–6 × 1–1.7 mm, glabrous; pollen spheroid. |
Fruiting pedicels | erect, straight, 3–9 mm, glabrous or sparsely pubescent. |
ascending to divaricate-ascending, straight, 3–8 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 to divaricate-ascending, not appressed to rachis, not secund, straight, edges parallel, 3.5–6.2 cm × 1.2–1.5 mm; valves glabrous; ovules 58–80 per ovary; style 0.8–1.5 mm. |
Seeds | usually uniseriate, rarely sub-biseriate, 1.5–2(–2.5) × 1–1.4 mm; wing continuous, 0.3–1 mm wide. |
uniseriate, 1.1–1.3 × 0.9–1 mm; wing continuous, 0.05–0.1 mm wide. |
Boechera paupercula |
Boechera cascadensis |
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Phenology | Flowering Jun–Aug. | Flowering Jun. |
Habitat | Rock outcrops, talus slopes, gravelly soil in alpine and subalpine habitats | Basaltic cliffs and rocky slopes in subalpine areas |
Elevation | 2400-3400 m (7900-11200 ft) | ca. 1900 m (ca. 6200 ft) |
Distribution |
CA; ID; OR; WA; WY
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OR; WA |
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. Morphological evidence suggests that Boechera cascadensis is an apomictic species that arose through hybridization between B. microphylla and B. paupercula (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison). It is known from two collections: the type specimens from Kittitas County, Washington, and a more recent collection from Baker County, Oregon. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 394. | FNA vol. 7, p. 369. |
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 microphylla var. thompsonii |
Name authority | (Greene) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 75. (2006) | Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 260. (2007) |
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