Boechera tularensis |
Boechera holboellii |
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Tulare rockcress |
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Habit | Biennials or perennials; short-lived; apomictic; caudex present or absent. | Biennials or perennials; short-lived; apomictic or sexual; caudex present or absent. |
Stems | 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. |
usually 1 per caudex branch, arising from center of rosette near ground surface, 2–6.7 dm, densely pubescent proximally, trichomes short-stalked, 4–8-rayed, 0.1–0.3 mm, glabrous or sparsely pubescent distally. |
Basal leaves | 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. |
blade oblanceolate, 2–5 mm wide, margins entire, sometimes ciliate near petiole base, trichomes (usually simple), to 0.7 mm, surfaces sparsely to moderately pubescent, trichomes short-stalked, 4–8-rayed, 0.1–0.3 mm. |
Cauline leaves | 7–17, often concealing stem proximally; blade auricles 2–5 mm, surfaces of distalmost leaves sparsely pubescent or glabrous. |
7–40, often concealing stem proximally; blade auricles 1–4 mm, surfaces of distalmost leaves glabrous or sparsely pubescent. |
Racemes | 19–39-flowered, usually unbranched. |
10–60-flowered, usually unbranched. |
Flowers | divaricate to pendent at anthesis; sepals pubescent; petals white to pale lavender, 6–7 × 1.2–2 mm, glabrous; pollen spheroid. |
divaricate to pendent at anthesis; sepals pubescent; petals white, 4–8 × 1–2 mm, glabrous; pollen ellipsoid or spheroid. |
Fruiting pedicels | reflexed, recurved proximally, 5–13 mm, glabrous. |
descending to reflexed, most abruptly recurved near base, 5–10 mm, glabrous or sparsely pubescent, trichomes appressed, branched. |
Fruits | 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. |
descending to reflexed, not appressed to rachis, strongly secund, often curved, edges parallel, 0.35–0.65 cm × (2–)2.2–2.5 mm; valves glabrous; ovules 80–102 per ovary. |
Seeds | sub-biseriate, 2–2.5 × 1.1–1.5 mm; wing continuous, 0.15–0.25 mm wide. |
uniseriate to sub-biseriate, 1.4–1.7 × 1–1.2 mm; wing continuous, to 0.2 mm wide. |
2n | = 14, 21. |
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Boechera tularensis |
Boechera holboellii |
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Phenology | Flowering Jun–Jul. | Flowering Jul–Aug. |
Habitat | Rocky slopes in montane and subalpine habitats | Rocky slopes and gravelly soil near coast |
Elevation | 2400-3200 m (7900-10500 ft) | 100-300 m (300-1000 ft) |
Distribution |
CA |
Greenland |
Discussion | 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.) |
Both sexual diploid and apomictic triploid collections of Boechera holboellii are known; available data suggest that the triploid is an autopolyploid derivative of the sexual diploid but further study is needed. In the narrow circumscription adopted here, it appears to be restricted to Greenland (see discussion of B. quebecensis in M. D. Windham and I. A. Al-Shehbaz 2007b). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 410. | FNA vol. 7, p. 384. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis holboellii, Arabis holboellii var. tenuis, B. tenuis | |
Name authority | Windham & Al-Shehbaz: Harvard Pap. Bot. 12: 249. (2007) | (Hornemann) Á. Löve & D. Löve: Bot. Not. 128: 513. (1976) |
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