Published March 1989. A more recent revision exists. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
These thistles are native to Europe and the Middle East.
Some are not true thistles; for example, purple/Iberian and
yellow starthistle actually are knapweeds. All of these plants, however,
share a spiny, thorny, invasive nature and long-lasting, hard seed. These traits make people who use or manage land for recreation,...