Glaucous star thistle: pest

Page last updated: Monday, 6 July 2020 - 10:03am

Please note: This content may be out of date and is currently under review.

Glaucous star thistle (Carthamus leucocaulos) is an uncommon weed in Western Australia (WA). This article describes the nature of the plant.

Form: herbaceous — annual

Status: present in WA


An erect slightly hairy or cobwebby annual herb, 50-100 centimetres high, reproducing by seed. Native of Turkey and Greece (Aegean region).

Stems: White to purple, rigid and ribbed but not winged. Single stem usually branching in the upper half.

Leaves: Greenish white; rosette leaves deeply divided, lobes ending in a spine, sparsely glandular; stem leaves stiff and shiny, deeply divided into two to three pairs of segments 1.3-1.7 centimetres long, each ending in a spine.

Flowers: Florets pale purple, grouped in terminal solitary heads 10-13 centimetres diameter; outer bracts surrounding the flower are shiny and bent back. These are 2.5-3 times longer than the inner bracts.

Seed: Grey brown, four angled, sometimes with a pappus of stiff scales five to seven millimetres long.

Agricultural and economic impact

A crop and pasture weed.

Legal status

The Western Australian Organism List (WAOL) contains information on the legal status of this pest in Western Australia (WA). Search for glaucous star thistle in the WAOL using the scientific name Carthamus leucocaulos.

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