Carduus

Annuals or biennials [perennials], 30–200(–400) cm, spiny, ± tomentose, sometimes glabrate. Stems erect, simple to much branched, (spiny-winged). Leaves basal and cauline; petiolate or sessile; blade margins spiny dentate, often 1–2-pinnately lobed, faces glabrous or hairy, eglandular. Heads discoid, borne singly or 2–20 in dense clusters or corymbiform arrays. (Peduncles naked or leafy-bracteate, spiny-winged or not winged.) Involucres cylindric to spheric. Phyllaries many in 7–10+ series, linear to broadly ovate, bases appressed, margins entire, apices ascending to spreading or reflexed, acute, spine-tipped. Receptacles flat, epaleate, bearing setiform scales (“flattened bristles”). Florets several–many; corollas white to pink or purple, ± bilateral, tubes long, slender, throats short, campanulate, abruptly expanded from tubes, lobes linear; anther bases sharply short-tailed, apical appendages oblong; style branches: fused portions with slightly, minutely puberulent, swollen basal nodes, distally papillate or glabrous, distinct portions very short. Cypselae ovoid, slightly compressed, faces smooth, glabrous, attachment scars slightly lateral; pappi persistent or falling in rings, of many minutely barbed, basally connate bristles or setiform, minutely barbed scales (“minutely flattened bristles”). x = 8, 9, 10, 11, 13.

Distribution

Eurasia, Africa.

Discussion

Species ca. 90 (5 in the flora).

Selected References

None.

Lower Taxa

Carduus acanthoides, Carduus crispus, Carduus nutans, Carduus pycnocephalus, Carduus tenuiflorus

Key

1	Phyllary appendages 2–7 mm wide, usually wider than appressed bases; peduncles often elongate, distally wingless; heads often nodding, usually borne singly or in leafy corymbiform arrays; involucres 20–70 mm diam	Carduus nutans
1	Phyllary appendages 0.5–1.5 mm wide, usually narrower than appressed bases; peduncles short, if present, usually winged throughout or wingless only near tip; heads erect, 1–many, often clustered at branch tips; involucres 7–30 mm diam	> 2
2	Involucres spheric or hemispheric	> 3
2	Involucres cylindric or narrowly ellipsoid	> 4
3	Corollas 13–20 mm; heads 18–25 mm; involucres 14–20 mm; abaxial leaf faces glabrate except for long, curled, septate hairs along veins	Carduus acanthoides
3	Corollas 11–16 mm; heads 15–18 mm; involucres 12–17 mm; abaxial leaf faces sparsely to densely tomentose with fine, nonseptate hairs and often with curled, septate hairs along veins as well	Carduus crispus
4	Heads 1–5 at ends of branches; phyllaries not scarious-margined, ± persistently tomentose, distally scabrous on margins and faces	Carduus pycnocephalus
4	Heads 5–20 at ends of branches; phyllaries scarious-margined, glabrous or spar- ingly tomentose, distally ciliolate or glabrous	Carduus tenuiflorus