The Collaborative International Dictionary of English v.0.48:

Knotwort \Knot"wort`\ (n[o^]t"w[^u]rt`), n. (Bot.)
   A small, herbaceous, trailing plant, of the genus
   Illecebrum (Illecebrum verticillatum).
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Centinody \Cen*tin"o*dy\, n. [L. centum a hundred + nodus knot:
   cf. F. centinode.] (Bot.)
   A weed with a stem of many joints (Illecebrum
   verticillatum); also, the Polygonum aviculare or
   knotgrass.
   [1913 Webster]