TREATMENT FROM THE JEPSON MANUAL	previous taxon | next taxon Jepson Interchange (more information)
	©Copyright 1993 by the Regents of the University of California Print edition is available from the University of California Press

	The second edition of The Jepson Manual (2012) is available from the University of California Press
	See also the Jepson eFlora, which parallels the Second Edition

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.

CIRSIUM

THISTLE

David J. Keil and Charles E. Turner

Annual to perennial herb (sometimes short-lived, dying after flowering once)
Stem generally erect
Leaves: lower generally tapered or petioled, often wavy-margined, generally pinnately lobed, ± dentate, lobes and teeth spine-tipped, margin generally spiny-ciliate, glabrous to tomentose; upper generally sessile, ± reduced
Inflorescence: heads discoid, 1–many; involucre cylindric to spheric; phyllaries many, graduated in several series, outer spine-tipped; receptacle flat, long-bristly
Flowers generally many; corollas ± bilateral, white to red or purple, tube long, slender, lobes linear; anther bases sharply sagittate, tips oblong; style tip with slightly swollen node, appendage (above node) long, cylindric, branches very short
Fruit ovoid, glabrous; scar slightly angled; pappus bristles many, plumose, ± persistent or falling in ring
Species in genus: ± 200 species: North America, Eurasia
Etymology: (Greek: thistle)
Taxa difficult, incompletely differentiated, hybridize.

Native

C. arizonicum (A. Gray) Petr.

ARIZONA THISTLE

Perennial 2–10 dm; taproot ± woody
Stem often > 1 from base, thinly tomentose or ± glabrous
Leaves ± tomentose (especially below), becoming ± glabrous; lower 1–2 dm, tapered to spiny-winged petioles, oblong-obovate, ± lobed, lobes generally further lobed or toothed, main spines 5–15 mm; middle and upper not strongly reduced, clasping or short-decurrent
Inflorescence: heads generally few, short-peduncled, ± closely subtended by uppermost leaves; involucres 3–4 cm, 1.5–2 cm diam when fresh, cylindric or narrowly ovoid, sparsely tomentose; phyllaries linear or linear-lanceolate, entire, generally erect or ascending, outer and middle tipped with spines 10–20+ mm, inner with tips flat or short-spined, straight, often red or purple, puberulent
Flowers exserted; corollas 30–34 mm, red, tube 7–9 mm, throat 11–14 mm, lobes 12–13 mm
Fruit 4–6 mm, ± compressed, shiny brown; pappus 24–28 mm
Chromosomes: 2n=32
Ecology: Open forests, sagebrush scrub
Elevation: 2400–3700 m.
Bioregional distribution: s High Sierra Nevada, White and Inyo Mountains
Distribution outside California: to Utah, New Mexico
Flowering time: Jul–Aug
Synonyms: C. eatonii (A. Gray) B.L. Rob. & C. nidulum (M.E. Jones) Petr. misapplied
Variable, needs further study; close to C. nidulum
Horticultural information: TRY.