Description. Knapweed is a robust tap-rooted perennial non-indigenous invasive weed growing 40-120 cm (16-48”) tall. There are several similar species growing in our area, blooming white, purple or a white-purple mix. In it’s dormant state, the prickly Knapweed will stand with seedpods attached until they are knocked over by heavy wind or movement of animals or people. The seeds spread by sticking to animal coats, by rolling in the wind, or getting stuck to the undercarriage of vehicles.

Historical plant use. None found.

Unusual aspects of this plant. If you pick this plant to help control it’s spread, land-fill the seeds – do not compost as they will grow in your garden.