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alpine rockcress, arabis alpina

coast rock cress, rose rockcress

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. Perennials; (caudex simple or branched, covered with persistent petiolar remains); sparsely to moderately pubescent, trichomes simple, forked-stalked, or rarely cruciform or 3-rayed, stalked, stellate.
Stems

usually simple from base, erect to ascending, often branched proximally, (0.6–)1–2(–2.5) dm.

simple or few from base (caudex), erect, unbranched or branched (few) distally, 0.6–2.5(–3) dm, (usually pubescent throughout, rarely subglabrate).

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 0.5–3(–6) cm, (ciliate);

blade oblanceolate, spatulate, or obovate, (1.5–)2.1–3.5(–6) cm × (5–)8–20(–25) mm, margins entire or dentate, (ciliate), apex obtuse, surfaces pubescent or glabrous, trichomes simple and forked, sometimes mixed with 3- or 4-rayed stellate ones.

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.

(2 or) 3–6 (or 7);

blade oblong or ovate, 1–2(–4) cm × (2–)4–10(–15) mm, base not auriculate, margins entire or dentate, (ciliate), apex obtuse, surfaces pubescent as basal leaves.

Racemes

simple, (lax).

simple, (dense).

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 (purple), oblong, 5–7 × 1.5–2 mm, lateral pair saccate basally;

petals purple, spatulate or broadly so, (12–)14–18 × 4–7 mm, apex obtuse or rounded;

filaments 6–8 mm;

anthers narrowly oblong, 1.2–1.5 mm.

Fruiting pedicels

ascending to divaricate, 4–10(–12) mm.

ascending to erect, (3–)5–10(–15) mm.

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.

erect or nearly so, slightly torulose, 2–4 cm × 2–3 mm;

valves each with prominent midvein extending full length or rarely to middle;

ovules 20–28 per ovary;

style 0.2–1(–1.5) mm.

Seeds

narrowly winged throughout, ovate, 1–1.4 × 0.9–1.1 mm;

wing 0.1–0.2 mm wide.

narrowly winged throughout, orbicular or suborbicular, 2–2.5 mm in diam.;

wing 0.2–0.4 mm wide (wider distally).

2n

= 16.

= 16.

Arabis alpina

Arabis blepharophylla

Phenology Flowering Jun–Aug. Flowering Mar–Apr.
Habitat Crevices of limestone rocks, along streams, calcareous alpine meadows, Salix scrub on slopes with scree Rocky hillsides and bluffs, grassy hillsides, slopes
Elevation 0-2400 m (0-7900 ft) 50-200 m (200-700 ft)
Distribution
from FNA
NY; WA; NL; NU; QC; Greenland; Europe; sw Asia; n Africa; tropical Africa
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
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.)

Arabis blepharophylla is an attractive species on the gradual increase in cultivation as an ornamental. It is recorded from Contra Costa, Marin, San Francisco, San Mateo, Santa Cruz, and Sonoma counties; most of the records are based on older collections.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 7, p. 259. FNA vol. 7, p. 266.
Parent taxa Brassicaceae > tribe Arabideae > Arabis Brassicaceae > tribe Arabideae > Arabis
Sibling taxa
A. aculeolata, A. blepharophylla, A. caucasica, A. crucisetosa, A. eschscholtziana, A. furcata, A. georgiana, A. mcdonaldiana, A. modesta, A. nuttallii, A. olympica, A. oregana, A. patens, A. pycnocarpa
A. aculeolata, A. alpina, A. caucasica, A. crucisetosa, A. eschscholtziana, A. furcata, A. georgiana, A. mcdonaldiana, A. modesta, A. nuttallii, A. olympica, A. oregana, A. patens, A. pycnocarpa
Synonyms A. alpina var. glabrata
Name authority Linnaeus: Sp. Pl. 2: 664. (1753) Hooker & Arnott: Bot. Beechey Voy., 321. (1838)
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