Utah State University Extension
Scotch thistle (Onopordum acanthium) is an invasive species native to Eurasia. It was likely introduced into North America during the late 19th century (Young & Evans, 1969). Due to the plant’s size and prickles, a stand can damage pasture productivity, ruin campsites, or make trails nearly impassable. The thistle also outcompetes desirable plants and greatly reduces forage use by large animals. Since not all thistles are related or alike, it is essential to correctly identify Scotch thistle before making management decisions. This fact sheet provides information about identification, lifecycle and distribution, and management.
Zesiger, Cody; Hadfield, Jacob; Taylor, Kalen; and Ransom, Corey, "Identification and Management of Scotch Thistle (Onopordum acanthium L.) in Pastures, Rangelands, and Non-Crop Settings" (2021). All Current Publications. Paper 2199.