Annuals or perennials (sometimes coarse and/or robust, often prickly-spiny and thistlelike [subshrubs, shrubs, or trees]; rarely dioecious, e.g., some Cirsium spp.). Leaves basal and/or cauline; alternate; ± petiolate or sessile; (leaf bases often decurrent on stems) margins usually lobed to dissected, sometimes dentate or entire (usually spiny). Heads mostly homogamous (usually discoid, sometimes disciform or radiant, then peripheral florets usually pistillate or neuter, sometimes bisexual or with staminodes), borne singly or in corymbiform, paniculiform, or racemiform arrays (heads with 1 floret each aggregated into second-order heads in Echinops). Calyculi 0 (involucres sometimes closely subtended by leaflike peduncle bracts). Phyllaries usually persistent [readily falling], in (1–)3–5+ series, usually distinct, usually unequal, usually herbaceous (sometimes fleshy), margins (entire or denticulate to pectinate, sometimes spiny) and apices seldom notably scarious (apices often spinose or ± expanded into distinct, often fimbriate-fringed, pectinate, and/or spiny appendages). Receptacles flat to convex, usually epaleate (often pitted and often bristly-setose or densely hairy). Ray florets 0 (corollas of peripheral florets in radiant heads often notably enlarged, usually 5-lobed, sometimes zygomorphic and raylike or ± 2-lipped). Peripheral (pistillate) florets 0 or (in disciform heads) in 1–3+ series; corollas (usually present) usually yellow, sometimes ochroleucous or cyanic. Disc florets bisexual and fertile (rarely functionally staminate); corollas yellow, cyanic, or white, usually actinomorphic, lobes 5, usually narrowly triangular to ± linear, seldom deltate (sometimes unequal, corollas then ± zygomorphic); anther bases ± tailed, apical appendages usually oblong (filaments sometimes papillate to pilose; connate in Silybum); styles (bisexual, fertile florets) distally enlarged or swollen, usually dilated and/or with rings of hairs at or near point of bifurcation, abaxially smooth or papillate to hairy (at least distally, sometimes ± throughout), “branches” often connate, adaxially continuously stigmatic ± to tips, apices rounded to acute, appendages essentially none. Cypselae usually monomorphic within heads (often thick-walled, hard, nutlike, receptacular attachments basal or lateral, bases sometimes each with an elaiosome), usually ellipsoid, obovoid, or ovoid, sometimes rounded-prismatic, terete, 4–5-angled, or ± compressed, rarely beaked, bodies usually smooth, sometimes rugose or 10- or 20-nerved (glabrous or puberulent to villous; often with apical umbo and/or crown in addition to pappus); pappi (rarely 0) readily falling or persistent, usually of fine to coarse, barbellate to plumose bristles, sometimes of scales, sometimes both bristles and scales.

Distribution

Mostly Old World, especially Mediterranean, some species widely introduced.

Discussion

Genera 83, species 2500 (17 genera, 116 species in the flora).

The circumscription for Cardueae adopted here is the traditional one and includes the three elements (Cardueae in the narrow sense, Carlineae, and Echinopeae) recognized as tribally distinct by M. Dittrich (1977[1978]). Work by K. Bremer (1987) supported the Dittrich scheme. A traditional circumscription of Cardueae was maintained by J. L. Panero and V. A. Funk (2002).

Selected References

Dittrich, M. 1977[1978]. Cynareae—systematic review. In: V. H. Heywood et al., eds. 1977[1978]. The Biology and Chemistry of the Compositae. 2 vols. London. Vol. 2, pp. 999–1015.

Garcia-Jacas, N., A. Susanna, T. Garnatje, and R. Vilatersana. 2001. Generic delimitations and phylogeny of the subtribe Centaureinae (Asteraceae): A combined nuclear and chloroplast DNA analysis. Ann. Bot. (Oxford) 87: 503–515.

Howell, J. T. 1959. Distributional data on weedy thistles in western North America. Leafl. W. Bot. 9: 17–32.

Moore, R. J. and C. Frankton. 1974. The Thistles of Canada. Ottawa. [Canada Dept. Agric., Res. Branch, Monogr. 10.]

Susanna, A., N. Garcia-Jacas, D. E. Soltis, and P. S. Soltis. 1995. Phylogenetic relationships in tribe Cardueae (Asteraceae) based on ITS sequences. Amer. J. Bot. 82: 1056–1068.

Wagenitz, G. and F. H. Hellwig. 1996. Evolution of characters and phylogeny of the Centaureae. In: D. J. N. Hind et al., eds. 1996. Proceedings of the International Compositae Conference, Kew, 1994. 2 vols. Kew. Vol. 1, pp. 491–510.

Lower Taxa

Acroptilon, Amberboa, Arctium, Carduus, Carlina, Carthamus, Centaurea, Cirsium, Crupina, Cynara, Echinops, Mantisalca, Onopordum, Plectocephalus, Saussurea, Silybum, Volutaria

Key

1	Leaf margins spiny	> 2
1	Leaf margins not spiny (tips sometimes ± spinose-apiculate)	> 10
2	Florets 1 per head (heads in globose, second-order heads)	Echinops
2	Florets 3–250+ per head (heads borne singly or in ± open arrays, not in globose second-order heads)	> 3
3	Stems winged	> 4
3	Stems not or rarely winged (some Cirsium spp.)	> 5
4	Receptacles bearing setiform scales ("flattened bristles"), (not pitted); cypselar attachments slightly lateral; pappus bristles usually distinct, sometimes basally connate	Carduus
4	Receptacles not bristly (deeply pitted); cypselar attachments basal; pappus bristles basally connate	Onopordum
5	Leaves variegated (stamen filaments connate)	Silybum
5	Leaves not variegated (stamen filaments distinct)	> 6
6	Corollas yellow to orange, red, or ± purple; cypsela attachments lateral; pappi 0 or of distinct, minutely barbed (not plumose) setiform scales ("flattened bristles") or subulate scales	> 7
6	Corollas white or purplish to red; cypsela attachments basal or oblique-basal; pappi of basally connate, plumose setiform scales ("flattened bristles")	> 8
7	Heads discoid (all florets fertile); receptacles bearing subulate scales; cypselae 4-angled	Carthamus
7	Heads disciform (peripheral florets sterile); receptacles bristly ("flat- tened bristles"), cypselae terete, 20-ribbed	Centaurea
8	Receptacles scaly (sometimes bristly); cypsela attachments oblique- basal	Carlina
8	Receptacles densely bristly-setose; cypselar attachments basal	> 9
9	Involucres 35–100+ mm diam. (largest leaves 60–150 cm; recep- tacles becoming fleshy)	Cynara
9	Involucres 10–50 mm diam. (largest leaves 20–50(–110) cm; receptacles usually not notably fleshy)	Cirsium
10	Heads discoid (all florets bisexual and fertile)	> 11
10	Heads radiant or disciform (peripheral florets usually neuter)	> 15
11	Cypselar attachments ± lateral	> 12
11	Cypselar attachments basal	> 13
12	Phyllary appendages entire or lacerate, not fringed; pappi of ± caducous, dis- tally plumose bristles	Acroptilon
12	Phyllary appendages dentate or fringed; pappi 0 or if persistent, then non- plumose bristles or scales	Centaurea
13	Phyllary apices spiny, hooked; bristles of pappus distinct, not plumose	Arctium
13	Phyllary apices spiny or not, not hooked; setiform scales ("flattened bristles") of pappus basally connate, plumose	> 14
14	Receptacles densely long-bristly ("flattened bristles") (becoming fleshy); florets 100–250+	Cynara
14	Receptacles usually subulate-scaly, sometimes bristly or naked (not fleshy); florets 10–20	Saussurea
15	Heads disciform	> 16
15	Heads radiant	> 17
16	Phyllary appendages dentate or fringed, spiny or not; receptacles bristly ("flat- tened bristles")	Centaurea
16	Phyllary appendages 0 (apices acute, entire); receptacles bearing subulate scales	Crupina
17	Phyllary appendages 0	> 18
17	Phyllary appendages present	> 19
18	Biennials or perennials; spines on phyllary apices caducous; cypsela apices not coronate	Mantisalca
18	Annuals; spines on phyllary apices persistent; cypsela apices coronate.	Volutaria
19	Cypselae compressed (oblong; attachment scars rimmed, rims whitish, swollen), apices denticulate	Amberboa
19	Cypselae ± terete (barrel-shaped; attachment scars not rimmed), apices entire	> 20
20	Annuals; leaf margins mostly entire or denticulate to serrulate; cypsela attachment oblique-basal; involucres 20–40 mm diam.; phyllary bodies linear, margins entire, appendages fimbriate; corollas of peripheral florets 30–70 mm	Plectocephalus
20	Annuals, biennials, or perennials; leaf margins entire or toothed to pinnately lobed; involucres 10–25(–40) mm diam.; cypsela attachment lateral; phyllary bodies oblong to ovate or obovate, margins fimbriate, appendages fimbriate; corollas of peripheral florets 15–30(–45) mm	Centaurea