名詞 knapweed:

1. any of various plants of the genus Centaurea having purple thistlelike flowers

knap.weed

n.（名詞）
Any of various thistles of the genusCentaurea, having variously colored flowers grouped in a head with a spiny involucre.
黑矢車菊：一種屬于矢車菊屬 的薊屬植物，其花有多種顏色，聚集在有刺狀花被的頭狀花序里

來源：
Middle English knopwed
中古英語 knopwed
knop [knob] from Old English cnop
knop [圓塊] 源自 古英語 cnop
wed [weed] * see weed
wed [雜草] *參見 weed