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

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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