Arabis oregana |
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Oregon rock-cress |
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Habit | Perennials; (caudex simple or branched, with some persistent petiolar remains); sparsely to moderately pubescent, trichomes bulbous-based, simple and long-stalked, forked, (to 2 mm), these often mixed with fewer 3-rayed, stalked stellate ones. |
Stems | simple or few from base (caudex), erect, unbranched distally, (0.6–)1.7–4.5(–5) dm, (usually pubescent throughout, rarely subglabrate, coarsely hirsute, trichomes simple, mixed with forked ones). |
Basal leaves | petiole 0.5–2(–3) cm, (ciliate); blade oblanceolate to obovate, (1–)2–5(–9) cm × (5–)8–18(–22) mm, margins entire or repand to dentate, (ciliate), apex obtuse, surfaces pubescent or glabrous, trichomes simple and forked, sometimes mixed with 3-rayed stellate ones. |
Cauline leaves | 3–6 (or 7); blade oblong, 1–3(–6) cm × 2–7(–15) mm, base not auriculate, margins entire or dentate, (ciliate or not), apex obtuse, surfaces pubescent as basal leaves or glabrous. |
Racemes | simple, (dense). |
Flowers | sepals (purple), oblong, (5–)6–8 × 1.5–2 mm, lateral pair saccate basally; petals purple or pink, spatulate, (10–)12–15(–16) × (3–)4–5 mm, apex obtuse; filaments (4–)5–8 mm; anthers narrowly oblong, 1.2–1.8 mm. |
Fruiting pedicels | ascending to erect, 5–10 mm, (pubescent or glabrous). |
Fruits | erect or nearly so, slightly torulose, (3–)4.5–6 cm × 1.5–2 mm; valves each with prominent midvein; ovules 24–30 per ovary; style 0.5–1 mm. |
Seeds | narrowly winged distally or not winged, oblong, 1.8–2.2 × ca. 1 mm; wing ca. 0.1 mm wide. |
2n | = 32. |
Arabis oregana |
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Phenology | Flowering Apr–May. |
Habitat | Moist granitic soil, rocky hillsides, chaparrals, steep banks |
Elevation | 500-1000(-1400) m (1600-3300(-4600) ft) |
Distribution |
CA; OR
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Discussion | Arabis oregana is known from Napa and Siskiyou counties (California) and Jackson County (Oregon). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 264. |
Parent taxa | Brassicaceae > tribe Arabideae > Arabis |
Sibling taxa | |
Synonyms | A. purpurascens, A. furcata var. purpurascens |
Name authority | Rollins: Rhodora 43: 349. (1941) |
Web links |