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.
ARABIDOPSIS
Annual, perennial herb
Stems 1–few, branched or not, slender
Leaves: basal in rosette, petioled; cauline sessile, base tapered or lobed, clasping stem or not
Inflorescence terminal, open
Flower small; sepal bases not sac-like; petals white, pale purple, or yellowish
Fruit linear, glabrous; pedicel ascending; style short or 0
Seeds many, ± 1 row per chamber, plump; wing 0; embryonic root at back of 1 cotyledon
Species in genus: Few but controversial number of species: Eur, Asia, 1 native to North America
Etymology: (Greek: resembling Arabis )
| Introduced |
A. thaliana (L.) Heynh.
MOUSE-EAR CRESS, THALE CRESS
Annual, freely branched
Stem 1–4 dm; hairs below simple, spreading, above 0
Leaves: basal oblanceolate, entire or minutely dentate, hairs coarse, branched; cauline few, base tapered
Flower: petals white
Fruit 1–1.5 cm, < 1 mm wide, linear, ± cylindric to ± flat; pedicel erect to ascending, 5–10 mm, slender
Seed < 1 mm, oblong
Chromosomes: 2n=10
Ecology: Uncommon. Disturbed, open ground
Elevation: < 1000 m.
Bioregional distribution: North Coast, Inner North Coast Ranges, San Francisco Bay Area, expected elsewhere
Distribution outside California: to e US (where abundant); native to Europe
Often used in experimental genetics, physiology, biochemistry.
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