Plants of South Eastern New South Wales

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Centaurea calcitrapa

Common name

Star thistle

Family

Asteraceae

Where found

Weed. Woodland, grassy areas, roadsides, wasteland and cultivated areas. Western Slopes, ACT, and tablelands. Occasionally in the Sydney area.

Notes

Introduced annual or biennial herb to 1 m high. Bracts on the flower heads spiny. Stems much-branched, grooved; stems and leaves with coarse hairs. Basal leaves short-lived, to 20 cm long, to 50 mm wide, deeply dissected, the margins of the lobes toothed. Stem leaves alternating up the stems, the lower stem leaves lobed, to 2–8 cm long, 10–30 mm wide, dark green; upper leaves entire, 2–4 mm wide, becoming linear. Flower heads 10-15 mm long below the 'petals', 6–10 mm in diameter, oval to cylindrical. Florets ('petals') pale purple, pink, or white, 15–20 mm long. Flower heads single. Flowering: spring–summer.

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=Centaurea~calcitrapa
(accessed 7 January, 2021)