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. platysperma A. Gray
Perennial; caudex branched; hairs generally 3–5-rayed
Stems several–many, simple or often branched above, ± decumbent to erect, hairy to glabrous
Leaves: basal many, 2–6 cm, oblanceolate, entire, tip acute to obtuse; cauline few, well spaced, sessile, 1–1.5 cm, oblong to linear-lanceolate, upper glabrous
Flower: petals spoon-shaped, pink, rarely whitish
Fruit erect to ascending, 3–7 cm, 3–5 mm wide, straight, flat; tip acuminate; pedicel ascending to ± spreading, 5–15 mm, glabrous; style < 1 mm to 0
Seed round; wing wide
Ecology: Rocky slopes, ridges
Elevation: 1300–3600 m.
Bioregional distribution: Outer North Coast Ranges, Cascade Range, High Sierra Nevada, Great Basin Floristic Province
Distribution outside California: Oregon, Nevada
| Native |
var. howellii (S. Watson) Jeps.
Stem simple, 0.5–2(3) dm
Leaves: basal glabrous; cauline bases clasping stem or not
Ecology: Rocky slopes, ridges
Elevation: 3000–3600 m.
Bioregional distribution: Outer North Coast Ranges, Cascade Range, High Sierra Nevada, Great Basin Floristic Province
Distribution outside California: Oregon, Nevada
Flowering time: Jul–Aug
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