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. remotifolium (Hook.) DC.

Biennial or perennial herb 3–15 dm, ± tomentose (at least when young), taprooted
Stem 1–several, often much-branched
Leaves ± persistently tomentose below, generally becoming ± glabrous above; lower 1.5–5 dm, petioles spiny, coarsely dentate or ± 1–2 X lobed and dentate, main spines 1–5 mm; cauline gradually reduced, well separated or crowded, often ± clasping, uppermost bract-like
Inflorescence: heads 1–several, ± clustered; peduncles 0–12 cm; involucres (1)2–3 cm, (1)1.5–4.5 cm diam, hemispheric or bell-shaped, ± persistently tomentose or becoming glabrous, sometimes cobwebby; phyllaries linear to widely oblong, outer entire or spiny-ciliate, with spine tips 1–3 mm, middle and inner tips flat, tapered, entire, or spiny-ciliate and sometimes widened into spiny-fringed or irregularly toothed appendages
Flowers: corollas (16)22–25 mm, white to purple, tube (6)8–12 mm, throat (6)8–10 mm, lobes 4–6 mm
Fruit 5–7 mm, compressed, dark; pappus 15–21 mm
Chromosomes: 2n=34
Ecology: Grassy areas, openings in woodlands, forests, sometimes on serpentine
Elevation: < 2000 m.
Bioregional distribution: Northwestern California, n Central Coast, San Francisco Bay Area
Distribution outside California: to Washington, s Wyoming, Colorado
Synonyms: var. odontolepis Petr.; C. acanthodontum S.F. Blake; C. amblylepis Petr.; C. callilepis (Greene) Jeps., C. c. var. pseudocarlinioides (Petr.) J.T. Howell