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

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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bioregional map for SONCHUS%20asper%20subsp.%20asper being generated
 
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Retrieve Jepson Interchange Index to Plant Names entry for Sonchus asper subsp. asper
Retrieve dichotomous key for Sonchus
Retrieve multiple-entry key (MEKA) for Sonchus
Overlay Consortium of California Herbaria specimen data by county on this map
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