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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.

CHAENACTIS

PINCUSHION

James D. Morefield

Annual to subshrubs, generally ± hairy
Leaves alternate or basal, generally petioled, reduced upward, entire and linear or generally elliptic to ovate or obovate and 1–4-pinnately lobed; 1° lobes longest near middle or base of blade
Inflorescence: heads discoid (but outer flowers often enlarged, ± ray-like), 1–many per stem, generally in terminal cymes; peduncle generally hairy like phyllary bases; involucre generally < 15 mm diam, cylindric to obconic or hemispheric; phyllaries in 1–2 ± equal series, generally linear to lanceolate, tips generally ± flat, generally ± green; receptacle flat to rounded, generally naked
Flowers 10–many; corollas radial (outer, if enlarged, ± bilateral), generally white to pinkish or yellow, generally opening in daytime; anthers generally exserted
Fruit club-shaped, generally not compressed, stiffly hairy; pappus 0 or of 4–20 fringed scales in 1–few series
Species in genus: 18 species: w North America
Etymology: (Greek: gaping ray, from enlarged outer corollas of some)
Reference: [Mooring 1980 Amer J Bot 67:1304–1309]
Spp. of sect. Chaenactis hybridize.

Native

C. artemisiifolia (A. Gray) A. Gray

Annual, branched above middle, robust
Stem generally 1, erect, < 10(20) dm, whitish scaly-puberulent below and on leaves, hairs thinning with age
Leaves < 15(–20) cm, not fleshy; basal rosette withering; largest blades (2)3–4-pinnately lobed, 1° lobes 5–10 pairs, ± crowded, longest near base, tips flat
Inflorescence: heads generally several per stem; peduncles < 7 cm; involucre hemispheric, densely wavy-hairy; longest phyllaries 7–10 mm, tips erect, ± rigid, sharp
Flowers: corollas radial, 5–7 mm, ± equal, white to pinkish
Fruit 4–7 mm, compressed; pappus 0
Chromosomes: 2n=16
Ecology: Open slopes, disturbed areas
Elevation: < 1600 m.
Bioregional distribution: Transverse Ranges, Peninsular Ranges
Distribution outside California: n Baja California
Much like C. lacera Greene of Baja CA.

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