Boechera rollei |
Boechera tularensis |
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Rolle's rock-cress |
Tulare rockcress |
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Habit | Perennials; long-lived; sexual; caudex woody. | Biennials or perennials; short-lived; apomictic; caudex present or absent. |
Stems | usually 1 per caudex branch, arising from center of rosette, elevated above ground surface on woody base, 1.5–2.5 dm, glabrous throughout. |
usually 1 per caudex branch, arising from center of rosette near ground surface, 2–7 dm, sparsely to densely pubescent proximally, trichomes subsessile, sub-malpighiaceous, 0.3–0.6 mm, glabrous distally. |
Basal leaves | blade oblanceolate, 3–8 mm wide, margins entire, ciliate proximally, trichomes (simple), 0.2–0.7 mm, surfaces glabrous or sparsely pubescent, trichomes short-stalked, 2–4-rayed, 0.2–0.4 mm. |
blade oblanceolate, 3–7 mm wide, margins entire, ciliate proximally, trichomes (simple), to 0.8 mm, surfaces sparsely to densely pubescent, trichomes subsessile, 2–5-rayed, 0.2–0.55 mm. |
Cauline leaves | 6–12, sometimes concealing stem proximally; blade auricles 0.5–2.5 mm, surfaces of distalmost leaves glabrous. |
7–17, often concealing stem proximally; blade auricles 2–5 mm, surfaces of distalmost leaves sparsely pubescent or glabrous. |
Racemes | 3–7-flowered, unbranched. |
19–39-flowered, usually unbranched. |
Flowers | divaricate-ascending at anthesis; sepals glabrous; petals creamy white, 8–11 × 2–2.5 mm, glabrous; pollen ellipsoid. |
divaricate to pendent at anthesis; sepals pubescent; petals white to pale lavender, 6–7 × 1.2–2 mm, glabrous; pollen spheroid. |
Fruiting pedicels | strongly curved proximally, 4–6 mm, glabrous. |
reflexed, recurved proximally, 5–13 mm, glabrous. |
Fruits | pendent, not appressed to rachis, not secund, straight to slightly curved, edges undulate (not parallel), 3.5–6 cm × 2.5–3.5 mm; valves glabrous; ovules 14–22 per ovary; style 0.5–1 mm. |
reflexed, rarely appressed to rachis, not secund, straight, edges parallel, 4–7(–8.5) cm × 2–2.3 mm; valves glabrous; ovules 88–104 per ovary; style 0.3–0.7 mm. |
Seeds | uniseriate, 3–4 × 1.5–2 mm; wing distal and proximal, 0.3–0.6 mm wide. |
sub-biseriate, 2–2.5 × 1.1–1.5 mm; wing continuous, 0.15–0.25 mm wide. |
Boechera rollei |
Boechera tularensis |
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Phenology | Flowering Aug. | Flowering Jun–Jul. |
Habitat | Peridotite rocks on sparsely forested slopes | Rocky slopes in montane and subalpine habitats |
Elevation | 1600-1800 m (5200-5900 ft) | 2400-3200 m (7900-10500 ft) |
Distribution |
CA |
CA |
Discussion | Boechera rollei is easily distinguished from the habitally similar B. suffrutescens by its longer (8–11 versus 4.5–6 mm) petals, narrower (2.5–3.5 versus 3–6 mm) fruits, and narrower (0.3–0.6 versus 0.8–1.5 mm) seed wings. This distinctive sexual species is known only from the vicinity of the type locality on the divide between the Applegate and Klamath Rivers in Siskiyou County. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Morphological evidence suggests that Boechera tularensis is an apomictic species that contains three different genomes, one each from B. rectissima, B. retrofracta, and B. stricta. It is most often confused with B. pinetorum and B. retrofracta, but is easily distinguishable from both (see M. D. Windham and I. A. Al-Shehbaz 2007b for detailed comparison). It is known from the southern Sierra Nevada (Fresno and Tulare counties). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 403. | FNA vol. 7, p. 410. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis rollei | |
Name authority | (Rollins) Al-Shehbaz: Novon 13: 389. (2003) | Windham & Al-Shehbaz: Harvard Pap. Bot. 12: 249. (2007) |
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