TREATMENT FROM THE JEPSON MANUAL	previous taxon | next taxon Jepson Interchange (more information)
	©Copyright 1993 by the Regents of the University of California Print edition is available from the University of California Press

	The second edition of The Jepson Manual (2012) is available from the University of California Press
	See also the Jepson eFlora, which parallels the Second Edition

BRASSICACEAE

MUSTARD FAMILY

Reed C. Rollins, except as specified

Annual to subshrub
Leaves generally basal and cauline, alternate, generally simple; stipules 0
Inflorescence: generally raceme
Flower bisexual; sepals 4, free; petals (0)4, free, generally white or yellow, often clawed; stamens generally (2,4)6, generally 4 long, 2 short; ovary 1, superior, chambers generally 2, septum membranous, connecting 2 parietal placentas, style 1, stigma simple or 2-lobed
Fruit: generally capsule ("silique") with 2 deciduous valves, sometimes breaking transversely or indehiscent
Seeds 1–many per chamber
Genera in family: 300+ genera, 3000+ species: worldwide, especially cool regions; some cultivated for food (especially Brassica, Raphanus ) and ornamental
Recent taxonomic note: Recently treated to include Capparaceae [Rodman et al. 1993 Ann Missouri Bot Gard 80:686–699; Rollins 1993 Cruciferae of Continental North America. Stanford Univ Press]
Family description, key to genera by Robert A. Price.

ARABIS

ROCK CRESS

Biennial, perennial herb; base woody or not; hairs 0 to dense, simple, forked, stellate, or multibranched; caudex branched or not
Stem branched or not, cylindric, leafy
Leaves: basal petioled, entire or dentate; cauline generally sessile, entire or dentate, base often lobed, often clasping stem
Inflorescence: bracts 0
Flower erect to reflexed; sepals erect; petals spoon-shaped to oblong and narrowed at base or narrowly obovate, white to deep purple, rarely straw-colored
Fruit erect to reflexed, linear, straight to curved, flat parallel to septum, rarely ± cylindric
Seeds ± many, generally 1 row per chamber, flat or plump, winged or not; embryonic root at edges of both cotyledons
Species in genus: ± 120 species: temp North America, Eurasia, Africa
Etymology: (Latin: of Arabia)

Native

A. microphylla Nutt. var. microphylla

SMALL-LEAVED ROCK CRESS

Perennial; caudex branched, underground; hairs generally multibranched, some simple
Stems several–many, branched or generally not, 1–2(3) dm in CA, slender; hairs spreading below, 0 above
Leaves: basal 5–29 mm, linear to narrowly oblanceolate, entire, greenish, tip acute, hairs minute; cauline few, sessile, 1–2 cm, narrowly lanceolate, base lobed, ± clasping stem
Flower: petals spoon-shaped, pale rose to purplish
Fruit ± ascending to spreading, 2–6 cm, ± 1 mm wide, straight to downcurved, glabrous; pedicel spreading to ascending, 5–15 mm, slender, ± glabrous; style < 1 mm or ± 0
Seed ± 1 mm, round; wing narrow
Chromosomes: 2n=14
Ecology: UNCOMMON. Rock crevices, basaltic or granitic outcrops
Elevation: 1700–2700 m.
Bioregional distribution: n High Sierra Nevada, Great Basin Floristic Province
Distribution outside California: to Washington, Montana, Wyoming

See the CNPS Inventory for information about endangerment and rarity.
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Retrieve Jepson Interchange Index to Plant Names entry for Arabis microphylla var. microphylla
Retrieve dichotomous key for Arabis
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