Southern Europe, the Mediterranean, and Central Asia
Plumeless thistle is an upright forb that typically grows as a biennial but can also behave as a winter annual. Plants grow 4 ft (1.2 m) tall on average from a fleshy taproot. Leaves have sharp spines along their wavy, whitish margins. They become more lobed as the plant ages. Stems are erect, highly branched, covered in bristly hairs, and have spiny wings along their entire length. Flower heads are solitary or in small clusters at the ends of stems. They have rows of needle-like bracts and 30–100 pink or purple florets. Seeds are straw-colored and topped by a tuft of fine hairs.
Introduced thistles currently infest millions of acres across North America, primarily occurring in or along roadways, waterways, agricultural fields, rangelands, pastures, forests, and disturbed areas. They are responsible for millions of dollars of damage annually in reduced agricultural yields and lowered forage value in grazing systems. Introduced invasive thistles can also displace native vegetation, negatively impacting wildlife and threatening the delicate ecological balance within many habitats.
Randall, C.B., J.E. Andreas, and J. Milan. 2024. Introduced Thistles: History and Ecology in North America. In: R.L. Winston, Ed. Biological Control of Weeds in North America. North American Invasive Species Management Association, Milwaukee, WI. NAISMA-BCW-2024-8- INTRODUCED THISTLES-P. https://bugwoodcloud.org/resource/files/29168.pdf