Arabis alpina |
Arabis patens |
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alpine rockcress, arabis alpina |
spreading rockcress |
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Habit | Perennials; (stoloniferous, with vegetative rosettes, loosely cespitose to somewhat pulvinate); sparsely to moderately pubescent, trichomes stalked, cruciform, stellate, mixed with simple and forked-stalked ones. | Biennials or, rarely, perennials; (short-lived, with caudex); usually densely hirsute (at least basally), trichomes simple (to 1 mm), sometimes mixed with stalked, forked ones. |
Stems | usually simple from base, erect to ascending, often branched proximally, (0.6–)1–2(–2.5) dm. |
simple or several from base (rosette), erect, often branched distally, (1.8–)2.5–4.5(–5.5) dm, (hirsute at least basally). |
Basal leaves | petiole 0–1 cm; blade spatulate, oblanceolate, oblong, or obovate, (0.4–)1–4(–5) cm × (3–)6–15(–20) mm, margins dentate to denticulate, apex obtuse or acute, surfaces usually pubescent, rarely subglabrate, trichomes stellate with simple rays. |
petiole (0.7–)2–5 cm; blade usually ovate to oblanceolate, rarely cordate, (0.8–)1.5–3 cm × 5–17 mm, margins dentate or serrate, surfaces sparsely to densely pubescent, trichomes simple or forked. |
Cauline leaves | 3–5(–6); blade oblong or ovate, 1–3 cm × 5–15 mm, base subcordate or auriculate, margins usually dentate, rarely subentire, apex acute or obtuse. |
(5–)8–20(–27), (overlapping or not); blade ovate to oblong or lanceolate, (2–)3–7.5(–9) cm × (10–)13–25(–35) mm, base amplexicaul, margins usually dentate or serrate, sometimes entire, surfaces hirsute. |
Racemes | simple, (lax). |
branched. |
Flowers | sepals oblong, 2.5–4(–4.7) × 1–2 mm, lateral pair conspicuously saccate basally; petals white, spatulate to obovate, 5–8(–9) × 2–3.5 mm, apex obtuse; filaments 3–5 mm; anthers oblong, 0.7–1.2 mm. |
sepals oblong, 2.5–4.5 × 1–1.5 mm, lateral pair slightly saccate basally; petals white, spatulate, (5–)6–9 × 2–3.5 mm, apex obtuse; filaments 3–5 mm; anthers oblong, 0.8–1.2 mm. |
Fruiting pedicels | ascending to divaricate, 4–10(–12) mm. |
ascending to divaricate-ascending, (7–)10–20(–24) mm, (glabrous or sparsely pubescent). |
Fruits | ascending to spreading, torulose, 1.7–3.5(–4) cm × 1–1.7 mm; valves each with midvein absent or obscure, along proximal 1/2; ovules 34–50 per ovary; style 0.3–0.6 mm. |
divaricate to erect-ascending, (not appressed to rachis), torulose, 2.2–4.6 cm × 0.8–1.2mm; valves each with prominent midvein extending to middle or full length; ovules 16–28 per ovary; style 0.5–2 mm, (slender). |
Seeds | narrowly winged throughout, ovate, 1–1.4 × 0.9–1.1 mm; wing 0.1–0.2 mm wide. |
narrowly winged distally, oblong, 1–1.6 × 0.6–0.8 mm; wing 0.05–0.1 mm. |
2n | = 16. |
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Arabis alpina |
Arabis patens |
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Phenology | Flowering Jun–Aug. | Flowering Apr–May. |
Habitat | Crevices of limestone rocks, along streams, calcareous alpine meadows, Salix scrub on slopes with scree | Rocky wooded slopes, shady stream banks, limestone ledges and bluffs |
Elevation | 0-2400 m (0-7900 ft) | 0-500 m (0-1600 ft) |
Distribution |
NY; WA; NL; NU; QC; Greenland; Europe; sw Asia; n Africa; tropical Africa
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DC; IN; KY; MD; NC; OH; PA; TN; VA; WV
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Discussion | Arabis alpina, the generic type, is variable. It is cultivated extensively for its attractive flowers, and it sometimes escapes from cultivation. There is disagreement as to whether one or more species should be recognized in this complex. European, some African, and most North American plants are recognized as A. alpina; most of the larger-flowered, southwestern Asian plants, which are most commonly cultivated, are recognized as A. caucasica or as A. alpina subsp. caucasica (Willdenow) Briquet. In my opinion, the morphological differences between the two (see key, couplet 3) support recognition of two species, as did R. C. Rollins (1993) and G. A. Mulligan (1996). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 7, p. 259. | FNA vol. 7, p. 262. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | A. alpina var. glabrata | Boechera patens |
Name authority | Linnaeus: Sp. Pl. 2: 664. (1753) | Sullivant: Amer. J. Sci. Arts 42: 49. (1842) |
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