A tough-stemmed Eurasian plant that typically has purple thistle-like flower heads, occurring chiefly in grassland and on roadsides.
Genus Centaurea, family Compositae: several species, including the widespread black knapweed (C. nigra) (also called and hardheads and )
- ‘The oil from the seeds of cotton thistles was extracted for fuel and knapweed, centaurea scabiosa, was believed to promote healing of bruises and wounds.’
- ‘Currently, most producers apply chemicals on rangeland in spring or summer, when knapweed begins to flower, but research is showing that fall application may be preferable.’
- ‘Spotted knapweed is not killed by fire, but sagebrush is.’
- ‘Invasive weeds such as cheatgrass and knapweeds have settled on some 125 million acres of the American West.’
- ‘In Montana, gall flies released to limit knapweed turn out to provide a food bonanza for white-footed mice.’