Adjective modifier

• black: Look out for wild carrot, white clover, weld, ragwort, thistle and black knapweed.

• common: The flowerheads of greater knapweed have long rays which are lacking in common knapweed.

• great: The flowerheads of greater knapweed have long rays which are lacking in common knapweed.

• lesser: Lesser knapweed grows in grassland where its reddish-purple thistle-like flowers appear from July to September.

• spotted: Dave Burch, the state's weed coordinator, estimated spotted knapweed costs the state's economy $ 42 million a year.

Modifies a noun

• broomrape: The reserve also boasts probably the largest numbers of the parasitic knapweed broomrape anywhere in the county.