FEIS: DISTRIBUTION AND OCCURRENCE:
"It is likely that there were multiple introductions of yellow starthistle to the United States ... and that contaminated alfalfa seed (Medicago sativa) was the primary vehicle for these introductions ... . Yellow starthistle seeds were found in adobe bricks from the period between 1824 and 1848 in California (Hendry 1931, ...). The plant was first collected in Oakland, California in 1869 and was most likely introduced from Chile, while introductions from 1899 to 1927 appear to be from Turkestan, Argentina, Italy, France and Spain "
UC Integrated Pest Management:
... It forms dense infestations and rapidly depletes soil moisture, thus preventing the establishment of other species. It is also poisonous to horses, causing a nervous disorder called “chewing disease” ...