Jepson Flora Project: Jepson Interchange    

 
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Jepson Interchange (more information)
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  • Up-to-date information about California vascular plants is available from the Jepson eFlora.

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. 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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