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.

CHAETADELPHA

G. Ledyard Stebbins

Species in genus: 1 sp.: w US
Etymology: (Greek: fused bristles)
Reference: [Tomb 1972 Madroño 21:459–462]

Native

C. wheeleri A. Gray

Perennial from branched caudex; sap milky; herbage glabrous
Stems 1–4 dm, much-branched
Leaves all cauline, alternate, 1–5 cm, linear to narrowly lanceolate (or scale-like), acute, entire
Inflorescence: heads ligulate, solitary on branchlets 2–5(7) cm; involucre 11–15 mm, narrowly cylindric; phyllaries in 2 series, outer 7–10 short, wide, inner 5 long, linear-oblong; receptacle naked
Flowers 5 per head; ligules 6–12 mm, pale lavender-white, readily withering
Fruit 8–12 mm, columnar, 4–5-ridged, glabrous; pappus double, of 5 stiff awns and generally many bristles, all fused at base, yellowish or tan
Chromosomes: 2n=18
Ecology: Sand dunes, desert scrub
Elevation: 900–1900 m.
Bioregional distribution: White and Inyo Mountains, n Mojave Desert (Eureka Valley)
Distribution outside California: se Oregon, w Nevada
Flowering time: May–Sep
Horticultural information: TRY.