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.

ATRICHOSERIS

TOBACCO-WEED, GRAVEL-GHOST

G. Ledyard Stebbins

Species in genus: 1 sp.: sw US
Etymology: (Greek: chicory-like plant without pappus)

Native

A. platyphylla (A. Gray) A. Gray

Annual, 2–18 dm, glabrous; sap milky
Stem erect
Leaves: basal and lowest cauline generally flat against soil, sessile or tapering to a short, winged petiole, 3–10 cm, obovate, obtuse, finely dentate, gray-green, often purple-tinged, especially below; cauline few, reduced to inconspicuous, triangular scales
Inflorescence: heads ligulate, 1.5–2.5 cm diam, few–many in an open scapose cyme; involucre 6–10 mm; phyllaries in 2–4 series, outer short, triangular to lanceolate, inner 10–15, ± equal; receptacle naked
Flowers fragrant; ligules white, readily withering
Fruit 4–4.5 mm with 5 thick, corky ribs, whitish; pappus 0
Chromosomes: 2n=18
Ecology: Desert valleys and washes
Elevation: < 1400 m.
Bioregional distribution: Desert
Distribution outside California: to Utah, Arizona
Flowering time: Mostly Mar–May
Horticultural information: TRY.