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. rollei Rollins
Perennial; caudex elevated, branched, woody
Stem simple, 1.5–2.5 dm, glabrous
Leaves: basal ± overlapped, 2–4 cm, entire, hairs 0 to sparse, generally forked or 3–4-rayed; cauline overlapped below, well spaced above, 1.2 cm, base of lower tapered, of upper lobed, clasping stem
Flower: petals 9–11 mm, spoon-shaped, cream-white
Fruit pendent to reflexed, 3.5–6 cm, 2–3 mm wide, glabrous; margin irregular; pedicel reflexed to recurved, lower 4–6 mm; style 0.5–1 mm
Seeds 1 row per chamber, oblong; wing on ends ± 0.5 mm, on sides narrow or 0
Ecology: Open, forested slopes among rocks
Elevation: 1500–1800 m.
Bioregional distribution: n Klamath Ranges (n Siskiyou Co.).
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