Jepson Flora Project: Jepson Interchange    

 
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Jepson Interchange (more information)
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ASTERACEAE

SUNFLOWER FAMILY

David J. Keil, Family Editor and author, except as specified

Annual to tree
Leaves basal or cauline, alternate to whorled, simple to compound
Inflorescence: 1° inflorescence a head, each resembling a flower, 1–many, generally arrayed in cymes, generally subtended by ± calyx-like involucre; flowers 1–many per head
Flowers bisexual, unisexual, or sterile, ± small, of several types; calyx 0 or modified into pappus of bristles, scales, or awns, which is generally persistent in fruit; corolla radial or bilateral (rarely 0), lobes generally (0)4–5; stamens 4–5, anthers generally fused into cylinder around style, often appendaged at tips, bases, or both, filaments generally free, generally attached to corolla near throat; pistil 1, ovary inferior, 1-chambered, 1-seeded, style 1, branches 2, generally hair-tufted at tip, stigmas 2, generally on inside of style branches
Fruit: achene, cylindric to ovoid, generally deciduous with pappus attached
Genera in family: ± 1300 genera, 21,000 species (largest family of dicots): worldwide. Largest family in CA. Also see tribal key to CA genera: Strother 1997 Madroño 44(1):1–28. See glossary p. 25 for illustrations of general family characteristics.

SILYBUM

MILK THISTLE

David J. Keil and Charles E. Turner

Annual or biennial
Leaves alternate, spiny-dentate, often coarsely lobed, dark green blotched white, ± glabrous; cauline reduced
Inflorescence: heads discoid, large; peduncles bracted; involucre ovoid to spheric; phyllaries overlapping in several series, tips of outer and middle spreading, lanceolate to ovate, spiny-fringed and -tipped; receptacle flat, white-bristly
Flowers many; corollas pink to purple, tube long, slender, throat abruptly wider, lobes linear; anther bases sharply short-sagittate, tips oblong; style tip with slightly swollen node, appendage long, cylindric, branches very short
Fruit ovoid, slightly compressed, glabrous, attachment slightly angled; pappus of many flat, minutely barbed bristles, falling in a ring
Species in genus: 2 species: Medit
Etymology: (Greek: name for thistle-like plants)

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