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Yellowspine Thistle (Cirsium ochrocentrum) 


Yellowspine thistle, Cirsium ochrocentrum, is designated by the California Department of Food and Agriculture as an "A" rated noxious weed. "A" rated noxious weeds are plants of known economic importance subject to enforcement action and are the highest priority for eradication by the CDFA and the SBCWMA. Populations of this weed are of very limited distribution in California. In Santa Barbara County, it is only known to occur on Santa Rosa Island. Large infestations could ruin a landscape for rangeland, recreation and wildlife habitat.


Cirsium ochrocentrum (family Asteraceae) is a patch-forming perennial that spreads by roots or seeds. C. ochrocentrum blooms from April - August. Flowers may be white, pink or pale purple and are composed of only disc flowers. The leaves, flowers and winged stems are covered with very sharp, stout spines. Small rosettes from creeping roots are often conspicuous in late summer.


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Cirsium ochrocentrum flower 

Cirsium ochrocentrum plant 

Cirsium ochrocentrum rosette