Jepson Flora Project: Jepson Interchange    

 
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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.

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. canovirens Rydb.

GRAY-GREEN THISTLE

Biennial or short-lived perennial herb 3–10 dm, from taproot
Stem generally 1, generally simple below, ± cobwebby and soft-hairy (hairs jointed, multicellular)
Leaves ± tomentose (especially lower surface), sometimes becoming ± glabrous; lower ± petioled, 1–2(3) dm, oblong or narrowly oblanceolate, generally lobed, main spines 5–10 mm; middle and upper smaller, decurrent as spiny wings, toothed or shallowly lobed
Inflorescence: heads 1–many in flat-topped to raceme-like clusters, sessile or peduncles generally 1–10 cm; involucres 1.5–2.5 cm, 1.5–3 cm diam, ovoid to hemispheric, ± loosely tomentose; phyllaries linear-lanceolate to ovate, ascending to spreading, midribs of outer and middle often with narrow glandular area, spines 5–10 mm, inner with tips flat, straight
Flowers: corollas 20–27 mm, dull white to pale purple, tube 7–10 mm, throat 7–10 mm, lobes 4–7 mm
Fruit 4–6 mm, dark brown, ± compressed; pappus 15–25 mm
Chromosomes: 2n=34
Ecology: Shrubby areas, open forests, roadsides
Elevation: 1600–3400 m.
Bioregional distribution: e High Sierra Nevada, Modoc Plateau, n East of Sierra Nevada
Synonyms: C. utahense Petr. misapplied
Needs further study; closely related to C. subniveum Rydb.

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bioregional map for CIRSIUM%20canovirens being generated
 
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Retrieve Jepson Interchange Index to Plant Names entry for Cirsium canovirens
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