Boechera howellii |
Boechera fecunda |
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Howell's flat-seed rock-cress, Howell's rockcress, pioneer rock-cress |
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Habit | Perennials; long-lived; sexual; caudex usually woody. | Perennials; usually long-lived; sexual; caudex often woody. |
Stems | usually 1 per caudex branch, arising from center of rosette near ground surface, 0.6–2(–3) dm, glabrous throughout. |
1 to several per caudex branch, arising from center and margin of rosette, slightly elevated on woody base or from near ground surface, 0.8–3 dm, densely pubescent throughout, trichomes short-stalked, 5–10-rayed, 0.1–0.2 mm. |
Basal leaves | blade narrowly oblanceolate, 1–7 mm wide, margins entire, ciliate proximally, trichomes (simple mixed with a few short-stalked, 2-rayed ones) 0.1–0.4 mm, surfaces glabrous. |
blade linear-oblanceolate, 1–5 mm wide, margins entire or with few teeth subapically, not ciliate, surfaces densely pubescent, trichomes short-stalked, 5–10-rayed, 0.1–0.2 mm. |
Cauline leaves | 2–4, not concealing stem; blade auricles (0–)0.2–1 mm, surfaces of distalmost leaves usually glabrous, rarely ciliate proximally. |
5–18, concealing stem proximally; blade auricles 0.5–2.5 mm, surfaces of distalmost leaves densely pubescent. |
Racemes | 2–5-flowered, unbranched. |
8–35-flowered, usually unbranched. |
Flowers | erect to ascending at anthesis; sepals glabrous; petals white to dark lavender, 4–8 × 1–2.5 mm, glabrous; pollen ellipsoid. |
erect to ascending at anthesis; sepals pubescent; petals purplish, 8–12 × 2.5–4.5 mm; pollen ellipsoid. |
Fruiting pedicels | ascending, straight, 4–10 mm, glabrous. |
erect to ascending, straight, 5–15 mm, pubescent, trichomes appressed, branched. |
Fruits | suberect to ascending, usually not appressed to rachis, not secund, straight to curved, edges often somewhat undulate (not parallel), 2.5–6.5 cm × 3–7 mm; valves glabrous; ovules 10–20 per ovary; style 0.05–0.3 mm. |
erect to ascending, often appressed to rachis, not secund, straight, edges parallel, 3–5.8 cm × 1.4–1.8 mm; valves densely pubescent throughout; ovules 34–68 per ovary; style 1–1.5 mm. |
Seeds | uniseriate, 3–6 × 2–4 mm; wing continuous, 1.3–2.5 mm wide. |
uniseriate, 1–1.5 × 0.8–1.2 mm; wing continuous, 0.5–0.1 mm wide. |
Boechera howellii |
Boechera fecunda |
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Phenology | Flowering Jun–Aug. | Flowering Apr–Jun. |
Habitat | Rock outcrops, talus slopes and gravelly soil in alpine and subalpine habitats | Rocky ground in sagebrush areas |
Elevation | 1800-3800 m (5900-12500 ft) | 1200-1800 m (3900-5900 ft) |
Distribution |
CA; NV; OR
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MT |
Discussion | Boechera howellii usually is subsumed under B. platysperma, but the two taxa are 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. Boechera fecunda is a distinctive sexual species known from Ravali and Silver Bow counties. Boechera fecunda is in the Center for Plant Conservation’s National Collection of Endangered Plants. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 384. | FNA vol. 7, p. 377. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis howellii, Arabis conferta, Arabis inamoena var. acutata, Arabis platyloba, Arabis platysperma var. howellii, Arabis platysperma var. imparata | Arabis fecunda |
Name authority | (S. Watson) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 69. (2006) | (Rollins) Dorn: Brittonia 55: 3. (2003) |
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