[f. KNOB sb. + WEED sb.]

1

  a.  = KNAPWEED; also applied to other British species of Centaurea. b. Name for Collinsonia canadensis, a N. American labiate plant.

2

1785.  Martyn, Rousseau’s Bot., xxvi. (1794), 401. Common or Black Knapweed, perhaps more properly Knobweed.

3

1879.  Britten & Holland, Plant-n., Knobweed (in allusion to the hard, round flower-heads), Centaurea nigra, C. Cyanus, and C. Scabiosa.

4

1888.  Syd. Soc. Lex., Knobweed, the Collinsonia canadensis.

5