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.

AMPHIPAPPUS

CHAFF-BUSH

Meredith A. Lane

Species in genus: 1 sp
Etymology: (Greek: double pappus)
Reference: [Porter 1943 Amer J Bot 30:481–483]

Native

A. fremontii Torr. & A. Gray

Shrub, glabrous
Stems much-branched, widely spreading to ascending, generally < 6 dm, striate, smooth, white above, grayish below; leafless stems spiny
Leaves short-petioled, generally < 2 cm, obovate or elliptic, entire, sometimes ± thick, light yellow- or gray-green
Inflorescence: heads radiate, in crowded, flat-topped clusters generally 3–5 cm wide; involucres cylindric, ± 5 mm, < 3 mm wide; phyllaries 7–12, ovate, whitish or pale green
Ray flowers 1–2, barely > involucre, tips 2- or 3-toothed, yellow
Disk flowers 3–7, staminate; corollas narrowly funnel-shaped, sinuses deep, lobes reflexed, style-branch appendages lanceolate to rounded
Fruit of ray flowers < or = 3 mm, hairy; pappus of 15–20 stout bristles fused at base, generally 1 mm; ovary of disk flowers < or = 1 mm, glabrous; pappus of 25 flattened, twisted bristles generally < or = 3 mm
Chromosomes: 2n=18
Ecology: Rocky or gravelly flats, slopes, canyons
Elevation: < 1600 m.
Bioregional distribution: c&e Mojave Desert
Distribution outside California: to Utah, Nevada, Arizona
Varieties not known to intergrade.

Native

var. fremontii

Leaves glabrous, sometimes gummy
Ecology: Habitats of sp.
Bioregional distribution: ne Mojave Desert
Distribution outside California: Nevada
Flowering time: Apr–May