Plants of South Eastern New South Wales
Cirsium arvense
Common name
Perennial thistle, Canada thistle
Family
Asteraceae
Where found
Weed. Mainly on roadsides and wasteland, occasionally in pasture, cropland, and disturbed woodland and grassland. Sydney area to Kanangra-Boyd National Park and west. Kosciuszko National Park east to Bega and Bombala.
Notes
Introduced perennial herb to 1 m high, forming large colonies. The only thistle in Australia that has spreading rhizomes. Leaves with spiny margins. Bracts on the flower heads spiny. Stems ridged, wingless, cobwebby to almost hairless. Leaves basal and alternating up the stems, upper surface dark green, lower surface with a white tomentum. Basal leaves to 10 cm long, to 40 mm wide, margins wavy to toothed. Stem leaves 1–7 cm long, to 20 mm wide, margins dissected. Male and female flowers on different plants. Flower heads globular to oval, 8–25 mm long, 8–25 mm in diameter. Florets pink to mauve, 12–18 mm long, female florets perfumed. Flower heads in many-flowered loose clusters. Flowering: Dec.–Feb.
General Biosecurity Duty all NSW. Noxious weed Vic.
PlantNET description: http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Cirsium~arvense (accessed 7 January, 2021)
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