Saffron Thistle

What is saffron thistle?

(Carthamus Ianatus)
Saffron thistle flowering springGeneric Weed Distribution Map
  • Saffron thistle is a weed of pasture and crops.
  • Saffron thistle is a declared weed in Tasmania under the Tasmanian Weed Management Act 1999. The importation, sale and distribution of saffron thistle are prohibited in Tasmania.

How to identify saffron thistle

  • Saffron thistle is an annual plant (living for one year) which grows to 90 cm tall. Saffron thistle belongs to the daisy family and is closely related to slender and spear thistles.
  • Saffron thistle seeds usually germinate with the onset of autumn rains although some seeds may germinate in winter and spring. The seedling grows into a rosette (a whorl of leaves close to the ground) which rarely exceeds 20 cm in diameter.
  • In spring a single stiff, wiry stem grows from the centre of the rosette and the rosette leaves wither and disappear. The stem leaves are very stiff with stout sharp spines at the tip and along the edges.
  • The stem divides into many branches with each branch carrying flower buds. The buds are enclosed in large spiny bracts very similar to the stem leaves. The flowers are slender, bright yellow florets which are partially hidden by the large bracts, making the flowers rather inconspicuous. Flowering occurs throughout November and December. The seed has a small fringe of stiff hairs which adheres to wool and clothing.
  • The plant generally dies during late autumn to early winter. Dead plants may remain standing for many months.
  • For help in identifying thistles in Tasmania, see Identifying Thistles in Tasmania and search the Dennis Morris Weeds and Endemic Flora database for saffron thistle illustrations. If you are still in doubt about the thistle you are dealing with, contact your Regional Weed Management Officer on 1300 368 550 for help.

Saffron thistle in Tasmania

  • Several small infestations of saffron thistle occur in Tasmania (see map). These infestations can usually be traced back to feed-grain imported from mainland states.
  • Saffron thistle is most common in run down pastures, roadsides and waste areas, particularly in areas of low rainfall and low soil fertility.
  • Saffron thistle competes strongly with crops and the stiff, wiry stems impede harvesting operations. The seed also contaminates grains and other crop seeds.
  • In pastures, dense infestations of saffron thistle impede grazing. Wool from sheep grazing in infested areas may become contaminated with sharp leaf fragments. Animals grazing in dense saffron thistle infestations can also suffer injury to their mouths and eyes from the spines.

Detailed management and control guidelines for saffron thistle can be found in the Saffron Thistle Control Guide. Refer also to Herbicides for Saffron Thistle Control. For further information see Weed Links and Resources.

See also
Saffron Thistle Control Guide
Herbicides for Saffron Thistle Control
Statutory Management Plan for Saffron Thistle
Weed Links and Resources

Other useful links
Pest Genie

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