Boechera saximontana |
Boechera pratincola |
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meadow rock-cress |
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Habit | Perennials; short-lived; apomictic; caudex usually not woody. | Perennials; usually short-lived; apomictic; caudex not woody. |
Stems | usually 1 per caudex branch, arising from center of rosette near ground surface, 0.7–3 dm, densely pubescent proximally, trichomes short-stalked, 2–6-rayed, 0.06–0.25 mm, glabrous distally. |
usually 1 per caudex branch, arising from center of rosette near ground surface, 2–6 dm, pubescent proximally, trichomes sessile, 2- or 3-rayed, 0.15–0.6 mm, glabrous distally. |
Basal leaves | blade narrowly oblanceolate, 1–3 mm wide, margins entire, ciliate near petiole base, trichomes (simple and spurred), to 0.4 mm, surfaces sparsely to densely pubescent, trichomes short-stalked, 4–8-rayed, 0.04–0.15 mm. |
blade oblanceolate, 1.5–5(–7) mm wide, margins usually entire, rarely denticulate, ciliate at petiole base, trichomes to 0.4 mm, surfaces pubescent, trichomes sessile, 2–4(–6)-rayed, 0.1–0.45 mm. |
Cauline leaves | 5–9, rarely concealing stem proximally; blade auricles to 0.3–1 mm, surfaces of distalmost leaves glabrous. |
(7–)13–42, concealing stem proximally; blade auricles 1–4 mm, surfaces of distalmost leaves sparsely pubescent apically. |
Racemes | 5–13-flowered, usually unbranched. |
(7–)14–45-flowered, usually unbranched. |
Flowers | ascending at anthesis; sepals pubescent; petals lavender, 4–5 × 0.5–0.8 mm, glabrous; pollen spheroid. |
ascending at anthesis; sepals glabrous; petals lavender, 6–10 × 1.5–2 mm, glabrous; pollen spheroid. |
Fruiting pedicels | divaricate-ascending, straight, 3–8 mm, glabrous. |
erect, straight, 5–12 mm, glabrous. |
Fruits | divaricate-ascending, not appressed to rachis, not secund, straight, edges parallel, (2.5–)3–4.7 cm × 1.2–1.7 mm; valves glabrous; ovules 78–112 per ovary; style 0.1–0.5 mm. |
erect, appressed to rachis, not secund, straight, edges parallel, 4–6.5 cm × 1.5–2 mm; valves glabrous; ovules 60–140 per ovary; style 0.1–0.3 mm. |
Seeds | uniseriate to sub-biseriate, 1.1–1.4 × 0.7–0.9 mm; wing continuous, 0.05–0.12 mm wide. |
sub-biseriate, 1.4–2 × 1–1.4 mm; wing continuous, 0.1–0.35 mm wide. |
Boechera saximontana |
Boechera pratincola |
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Phenology | Flowering Jun–Jul. | Flowering Jun–Aug. |
Habitat | Rocky soil in sagebrush and open conifer forests | Rocky slopes and soil patches in open areas and along forest edges |
Elevation | 2400-2900 m (7900-9500 ft) | 1900-3200 m (6200-10500 ft) |
Distribution |
ID; WY |
CA; ID; NV; OR
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Discussion | Boechera saximontana is an apomictic taxon that has been treated as a variety of either Arabis microphylla (R. C. Rollins 1941) or A. (Boechera) williamsii (Rollins 1993; R. D. Dorn 2001). It is easily distinguished from typical collections of those species (see M. D. Windham and I. A. Al-Shehbaz 2007b for detailed comparison), but it is likely that one (or both) were involved in its hybrid origin. It is known from Blaine, Custer, and Lemhi counties in Idaho, and Big Horn and Fremont counties in Wyoming. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Morphological evidence suggests that Boechera pratincola is an apomictic species that arose through hybridization between B. paupercula and B. stricta (see M. D. Windham and I. A. Al-Shehbaz 2007b for detailed comparison). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 404. | FNA vol. 7, p. 399. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis microphylla var. saximontana, Arabis pendulocarpa var. saximontana, Arabis williamsii var. saximontana, B. williamsii var. saximontana | Arabis pratincola, Arabis drummondii var. pratincola, Arabis nemophila |
Name authority | (Rollins) Windham & Al-Shehbaz: Harvard Pap. Bot. 12: 248. (2007) | (Greene) Windham & Al-Shehbaz: Harvard Pap. Bot. 12: 245. (2007) |
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