knapweed [
'næp`wid]
n. 黑矢车菊
knapweed[ noun ]
any of various plants of the genus Centaurea having purple thistlelike flowers
<noun.plant>
Knapweed \Knap"weed`\, n. (Bot.)
The black centaury ({Centaurea nigra}); -- so called from the
knoblike heads of flowers. Called also {bullweed}.
- They spend millions of dollars a year spraying herbicides, on spotted knapweed for example, which blankets half of Missoula County.