Boechera howellii |
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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. |
Stems | usually 1 per caudex branch, arising from center of rosette near ground surface, 0.6–2(–3) dm, glabrous throughout. |
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. |
Cauline leaves | 2–4, not concealing stem; blade auricles (0–)0.2–1 mm, surfaces of distalmost leaves usually glabrous, rarely ciliate proximally. |
Racemes | 2–5-flowered, unbranched. |
Flowers | erect to ascending at anthesis; sepals glabrous; petals white to dark lavender, 4–8 × 1–2.5 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | ascending, straight, 4–10 mm, glabrous. |
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. |
Seeds | uniseriate, 3–6 × 2–4 mm; wing continuous, 1.3–2.5 mm wide. |
Boechera howellii |
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Phenology | Flowering Jun–Aug. |
Habitat | Rock outcrops, talus slopes and gravelly soil in alpine and subalpine habitats |
Elevation | 1800-3800 m (5900-12500 ft) |
Distribution |
CA; NV; OR
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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.) |
Source | FNA vol. 7, p. 384. |
Parent taxa | |
Sibling taxa | |
Synonyms | Arabis howellii, Arabis conferta, Arabis inamoena var. acutata, Arabis platyloba, Arabis platysperma var. howellii, Arabis platysperma var. imparata |
Name authority | (S. Watson) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 69. (2006) |
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