Boechera falcifructa |
Boechera paupercula |
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boechera paupercula, littleleaf rockcress, small-flower rock-cress, tiny suncress |
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Habit | Perennials; usually long-lived; apomictic; caudex often woody. | Perennials; long-lived; (cespitose); sexual; caudex often woody. |
Stems | usually 1 per caudex branch, arising from center of rosette near ground surface, 1.5–4.5 dm, densely pubescent proximally, trichomes short-stalked, 4–9-rayed, 0.05–0.2 mm, glabrous or sparsely pubescent distally. |
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. |
Basal leaves | blade linear to narrowly oblanceolate, 1–4 mm wide, margins entire, ciliate at petiole base, trichomes (simple), to 0.5 mm, surfaces densely pubescent, trichomes short-stalked, 4–9-rayed, 0.05–0.2 mm. |
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. |
Cauline leaves | 5–9, not concealing stem; blade auricles 0.5–1 mm, surfaces of distalmost leaves sparsely pubescent. |
2–6, rarely concealing stem; blade auricles 0 (or 0.2–1.5) mm, surfaces of distalmost leaves glabrous. |
Racemes | 10–18-flowered, sparingly branched. |
3–8-flowered, unbranched. |
Flowers | divaricate-ascending at anthesis; sepals pubescent; petals lavender, 5–7 × 0.7–1.2 mm, glabrous; pollen spheroid. |
erect at anthesis; sepals glabrous or sparsely pubescent; petals lavender to purplish, 4–6(–7) × 1–2 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | divaricate-descending, gently curved downward, 6–12 mm, pubescent, trichomes appressed, branched. |
erect, straight, 3–9 mm, glabrous or sparsely pubescent. |
Fruits | divaricate-descending, not appressed to rachis, not secund, gently curved, edges parallel, 4.5–6 cm × 1.2–1.5 mm; valves glabrous; ovules 62–80 per ovary; style 0.5–1 mm. |
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. |
Seeds | uniseriate, 1.2–1.7 × 0.8–1.2 mm; wing mostly distal, 0.05–0.1 mm wide. |
usually uniseriate, rarely sub-biseriate, 1.5–2(–2.5) × 1–1.4 mm; wing continuous, 0.3–1 mm wide. |
Boechera falcifructa |
Boechera paupercula |
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Phenology | Flowering May–Jun. | Flowering Jun–Aug. |
Habitat | Rocky slopes and sandy soil in sagebrush or pinyon-juniper woodlands | Rock outcrops, talus slopes, gravelly soil in alpine and subalpine habitats |
Elevation | 1500-1800 m (4900-5900 ft) | 2400-3400 m (7900-11200 ft) |
Distribution |
NV |
CA; ID; OR; WA; WY
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Discussion | Of conservation concern. Morphological evidence suggests that Boechera falcifructa is an apomictic species that arose through hybridization between B. cobrensis and B. fernaldiana. It is more similar to the former, but is distinguished by its gently curved fruiting pedicels (versus strongly recurved or reflexed distally), narrower (1.2–1.5 versus 1.7–2.5 mm) fruits, more (62–80 versus 34–64) ovules per ovary, longer (0.5–1 versus 0.05–0.2 mm) styles, and narrower (0.05–0.1 versus 0.25–0.5 mm) seed wings. Although independently reproducing, B. falcifructa is known only from Elko and Lander counties, where the parental species grow in proximity. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 7, p. 377. | FNA vol. 7, p. 394. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis falcifructa | Arabis paupercula, Arabis lyallii var. nubigena, Arabis microphylla var. nubigena, Arabis nubigena |
Name authority | (Rollins) Al-Shehbaz: Novon 13: 385. (2003) | (Greene) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 75. (2006) |
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