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Jepson Interchange (more information)
©Copyright 1993 by the Regents of the University of California

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  • Up-to-date information about California vascular plants is available from the Jepson eFlora.

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.

SONCHUS

SOW THISTLE

G. Ledyard Stebbins

Annual to shrubs; sap milky
Stems erect, smooth, leafy
Leaves basal and cauline, alternate, ± entire to toothed and coarsely pinnate-lobed; cauline generally sessile, clasping
Inflorescence: heads ligulate, in cymes; involucre swollen at base; phyllaries generally in 3 series, outer many, short-triangular, those of inner 2 series linear, tapered; receptacle ± flat, naked
Flowers many; ligules yellow, readily withering
Fruit generally ± flat, beakless; pappus of many fine, white bristles
Species in genus: 54 species: Eurasia, Africa
Etymology: (Ancient Greek name)
Reference: [Boulos 1972–74 Bot Not 125:287–319, 126:155–196; 127:7–37,402–451]

Introduced

S. asper (L.) Hill subsp. asper

PRICKLY SOW THISTLE

Annual 1–12 dm
Stems mostly unbranched below inflorescence
Leaves: basal tapered to generally sessile bases; cauline sessile, clasping, upper often widest near base, basal clasping lobes rounded, strongly curved to coiled; blades dentate, sometimes ± lobed, teeth and lobes tipped with soft spines
Inflorescence: peduncles 0.5–5 cm, generally ± bristly-glandular; involucre 10–13 mm
Flowers: ligule ± 1/3 < tube
Fruit 2–3 mm, very flat, 3-ribbed on each face, otherwise smooth; pappus bristles ± 3 X fruit
Chromosomes: 2n=18
Ecology: Common. Weed in slightly moist waste places, gardens, along streams
Elevation: < 1900 m.
Bioregional distribution: California
Distribution outside California: to e US; native to Europe
Flowering time: Most of year
Much like S. oleraceus.

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