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.

CONYZA

Annual or perennial herb
Stems generally erect, leafy
Leaves alternate, linear to ± (ob)lanceolate, entire to pinnately dissected, obtuse to acute
Inflorescence: heads generally disciform (or minutely radiate), generally many in raceme- or panicle-like clusters; phyllaries in 2–3 equal or unequal series, free, linear to lanceolate, often narrowly scarious-margined, reflexed in age; receptacle naked
Pistillate flowers generally many; corollas white, pink, or cream, narrowly cylindric
Disk flowers ± few; corollas generally yellow, lobes short-triangular; style tips lanceolate, included or short-exserted
Fruit elliptic, compressed, puberulent; pappus of bristles
Species in genus: ± 50 species: especially tropical
Etymology: (Greek: flea; name of Pliny & Dioscorides for a fleabane)

Introduced

C. bonariensis (L.) Cronquist

Annual 20–120 cm, ± gray-hairy
Stems 1–several from base, strigose and long-soft-hairy
Leaves 1–9 cm, entire to shallowly lobed
Inflorescence: lateral clusters often overtopping central; peduncles generally 1–4 cm; fresh involucres 5–7 mm diam; phyllaries 2–6 mm, often purple-tipped, densely soft-hairy, whitish or dull brown inside when dry and reflexed, midvein green to purple, not resin-filled
Pistillate flowers very many; corollas 3–4 mm; ligule ± 0
Disk flowers 10–20; corollas 3.5–4 mm, greenish yellow
Fruit ± 1.5 mm; pappus 3–4 mm, generally ± reddish in age
Chromosomes: 2n=54
Ecology: Disturbed, generally urban sites
Elevation: generally < 1000 m.
Bioregional distribution: Central Western California, Southwestern California
Distribution outside California: to e N.America; native to S.America