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Purple Starthistle

Purple Starthistle

Purple Starthistle

(Centaurea calcitrapa)

Priority: -  Prevent

Tags: Agricultural | Terrestrial

Identification and Reproduction


  • This thistle grows up to 1.3 m tall. It is very branched and can appear bushy. 
  • Stems are hairless, grooved and covered in resin spots. 
  • Leaves on the upper stem are small and simple while lower stem leaves are lobed.

  • Stems and leaves are covered in fine, cobwebby hairs but will become smooth with maturity. 
  • Each inflorescence contains 25-40 disk flowers per head. Flower bracts are green or straw-coloured depending on season and covered in sharp yellow spines. 
  • Flowers are purple and bloom from July through September.  


Purple starthistle reproduces by seeds that can be viable for 3 years. 


Habitat & Ecology

  • Well adapted to various soil types. 
  • Slightly shade-intolerant. 
  • Often found on fields, roadsides, exposed areas, grasslands, rangelands and recently logged sites. 



  • Reduces foliage availability and displaces native species. 
  • Displaces desired crop species. 
  • Unpalatable to livestock. 


Prevention is a high priority for this plant.

  • Thoroughly clean shoes, clothing, pets, equipment and vehicles when leaving an infested site. 
  • Avoid transporting unknown soil and plant materials.

Mechanical/Manual Control: 

  • Avoid mowing as this can stimulate regrowth of stems. 
  • Hand-pulling or cutting can be effective for small patches. When cutting, sever roots at least 5 cm below the ground. 


For more information check out the Texas Invasive Species Institute page on Purple Star Thistle here

Header photo (Xemenendura)