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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.

CARDUUS

PLUMELESS THISTLE

David J. Keil and Charles E. Turner

Annual to perennial herb
Stems erect
Leaves alternate, reduced upward, decurrent as spiny wings, spiny-dentate and pinnately lobed, glabrous to tomentose; basal tapered to winged petiole; cauline sessile
Inflorescence: heads discoid, 1–20 at branch tips; involucre cylindric to spheric; phyllaries overlapping in several series, spine-tipped; receptacle flat, whitish bristly
Flowers: corollas white to pink or purple, tube long, slender, throat abrupt, short, lobes linear; anther bases short-sagittate, tips oblong; style with slightly swollen node, cylindrical above node, branches very short
Fruit ovoid, slightly compressed, glabrous; base slightly angled; pappus of many flat, minutely barbed, persistent bristles
Species in genus: ± 90 species: Eurasia, e Africa
Etymology: (Latin: ancient name)
Reference: [Howell 1959 Leaflets W Bot 9:17–29]

Introduced

C. acanthoides L.

PLUMELESS THISTLE

Biennial
Stems 3–15 dm, ± glabrous to loosely woolly, strongly spiny-winged
Leaves: basal 10–20 cm, spiny-toothed or pinnately lobed, generally sparsely hairy
Inflorescence: heads 1–5 in clusters; involucre 1–2.5 cm diam, spheric; phyllaries narrowly lanceolate, tips appressed to spreading
Flowers: corollas 14–20 mm, purple; tube 7–10 mm
Fruit 2.5–3 mm, golden to brown; pappus 11–13 mm
Chromosomes: 2n=16,20,22
Ecology: Roadsides, pastures, waste areas
Elevation: < 1300 m.
Bioregional distribution: Inner North Coast Ranges, n Sierra Nevada, San Francisco Bay Area, n Outer South Coast Ranges, Modoc Plateau
Distribution outside California: N.America.; native to Europe
Weedy. Scattered.

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