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Electronic Flora of South Australia
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Electronic Flora of South Australia species Fact Sheet

Cirsium arvense

Citation: Scop., Fl. Carniolica edn 2, 2:126 (1772).

Synonymy: Serralula arvensis L., Sp. Pl. 820 (1753).

Common name: Perennial thistle, creeping thistle, Canada thistle.

Perennial herb to 1 m high, with spreading rhizomes forming large colonies; stems erect, often unbranched below the inflorescence, wingless, striate, cobwebby to subglabrous; basal leaves oblanceolate, narrowed at the base, sinuate to dentate, to 10 cm long, with spiny margins; cauline leaves oblanceolate to lanceolate, subamplexicaul or very shortly decurrent at the base, pinnatifid, 1-7 cm long, spiny on margins, dark-green and sparsely cobwebby above, densely white-woolly below.

Capitula in a large loose corymb, 1-4 terminal on each branch, 12-25 mm long, containing florets of one sex only; involucre globose to ovoid; bracts lanceolate, the outer ones 3- or 4-seriate, spine-tipped, slightly pubescent; the inner ones shorter, acute, scarious; corolla pale-mauve, 12-18 mm long.

Achenes c. 3 mm long, smooth, pale-brown; pappus 20-25 mm long.

Published illustration: Parsons (1973) Noxious weeds of Victoria, p. 65.

Distribution:  On roadsides and in pastures.

  W.Aust.; N.S.W.; Vic.; Tas.   Native to Europe, Asia and North Africa.

Conservation status: naturalised

Flowering time: Dec. — Feb.

SA Distribution Map based
on current data relating to
specimens held in the
State Herbarium of South Australia

Biology: Only recorded once in S.Aust., but a serious and persistent weed of pastures in the other States.

Author: Not yet available

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