Jepson Flora Project: Jepson Interchange    

 
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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.

XANTHIUM

COCKLEBUR

Willard W. Payne

Annual
Leaves alternate, petioled, generally ± lobed, ± hairy
Inflorescence: staminate heads in clusters, involucre 0, receptacle chaffy; pistillate heads 2-flowered, 2-beaked, spiny, bur-like; phyllaries 0 or minute; chaff scales many, spirally arrayed, fused below, free tips spiny, hooked
Staminate flowers many; corolla translucent; filaments fused, attached to corolla tube base, anthers free; ovary slender
Pistillate flowers generally 2 per head; corolla 0; style branches long
Fruit 2, enclosed in bur, germinating in successive years; pappus 0
Species in genus: 2 species: worldwide
Etymology: (Greek: yellow, from fruit-extract dye)

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