Definitions

1. noun

A perennial herb of the family Rosaceae, especially Centaurea stoebe, native to Europe and Asia, but widely naturalized elsewhere, with spiny or thorny stems and small yellow or pinkish flowers; also, a similar plant, such as Centaurea diffusa or Centaurea repens.

“The invasive knopweed has taken over large areas of the local park and is choking out native plant species.”