Flora of North America species comparison

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Onopordum acanthium

Onopordum illyricum

cotton thistle, onoporde acanthe, Scotch cotton-thistle, Scotch-thistle, Scots thistle

Illyrian cottonthistle, Illyrian thistle
Habit Plants 50–250 cm, herbage canescent-tomentose throughout.
Stems

wings 0.5–2 cm wide.
Leaves

10–50 cm, margins shallowly to ± deeply 1–2-pinnatifid with 8–10 pairs of triangular lobes.
Involucres

30–60 mm diam (excluding spines) ± spheric, bases truncate to concave.
Corollas

purple, 25–35 mm.
Phyllaries

lanceolate to ovate, bases 3–8 mm wide, glabrous or ± cobwebby-tomentose, spines to 5 mm.
Heads

mostly borne singly at branch tips.
Cypselae

4–5 mm;

pappi of many whitish, plumose bristles 10–12 mm.
2n

= 34 (France).

Onopordum acanthium

Onopordum illyricum
Phenology Flowering summer (Jun–Aug).
Habitat Grasslands, fields, roadsides, oak woodlands
Elevation 200–500 m (700–1600 ft)
Distribution
from FNA
AL; AZ; CA; CO; CT; DE; FL; IA; ID; IL; IN; KS; KY; MA; MD; MI; MN; MO; MT; NE; NJ; NM; NV; NY; OH; OK; OR; PA; RI; TX; UT; VA; VT; WA; WI; WV; WY; BC; NB; NS; ON; QC; Eurasia
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; s Europe (Mediterranean region) [Introduced in North America; introduced in Australia]
[BONAP county map]
Discussion

Subspecies 3 (1 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Illyrian thistle is considered to be a noxious weed in California where efforts to eradicate it from the state’s flora have been implemented. This species has also invaded rangelands in Australia, where it is introduced.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 19, p. 88. FNA vol. 19, p. 88.
Parent taxa Asteraceae > tribe Cardueae > Onopordum Asteraceae > tribe Cardueae > Onopordum
Sibling taxa
O. illyricum, O. tauricum
O. acanthium, O. tauricum
Subordinate taxa
O. acanthium subsp. acanthium
Name authority Linnaeus: Sp. Pl. 2: 827. (1753) Linnaeus: Sp. Pl. 2: 827. (1753)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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(If the plant you're looking for doesn't show up in the auto-complete list, that means it either isn't described in Flora of North America yet, or it's listed under a synonym. And please note that Flora of North America is still missing several plant families, including Fabaceae, Apiaceae, Boraginaceae, and Polemoniaceae.)

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