Non-native Species of the Month-Plumeless thistle (Carduus acanthoides)
Plumeless Thistle is the spiniest of all thistles in Minnesota, with long spines covering the stem and leaf edges. It can be found in all sorts of habitats, ranging from disturbed soil and waste areas to invading high quality natural areas. Plumeless Thistle is a biennial, but produces massive amounts of seed that can form a monoculture where it is allowed to spread. Flowers form in mid-late summer in clusters or individually and are purple and small in size, about 1 inch wide. Plants obtain heights of 3-6 feet. It appears very similar to Bull Thistle and Nodding Thistle, but both of these have larger flowers. Management includes preventing seed formation by cutting flowers, pulling (with hefty gloves), and mowing or cutting plants close to the ground.
(above photo by Peter Dziuk of www.minnesotawildflowers.info)