| Noun | 1. | plume thistle - any of numerous biennial to perennial herbs with handsome purple or yellow or occasionally white flower heads thistle - any of numerous plants of the family Compositae and especially of the genera Carduus and Cirsium and Onopordum having prickly-edged leaves Cirsium, genus Cirsium - plume thistles Canada thistle, Cirsium arvense, creeping thistle - European thistle naturalized in United States and Canada where it is a pernicious weed Cirsium flodmanii, woolly thistle - thistle of western North America having white woolly leaves brook thistle, Cirsium rivulare - of central and southwestern Europe boar thistle, bull thistle, Cirsium lanceolatum, Cirsium vulgare, spear thistle - European thistle with rather large heads and prickly leaves; extensively naturalized as a weed in the United States |