The Collaborative International Dictionary of English v.0.48:

agueweed \agueweed\ n.
   1. 1 a gentian of East North America having clusters of
      bristly blue flowers.

   Syn: ague weed, five-flowered gentian, stiff gentian,
        Gentianella quinquefolia, Gentiana quinquefolia
        [WordNet 1.5]

   2. a perennial herb of the southeastern U. S. having
      white-rayed flower heads. It was formerly used in folk
      medicine.

   Syn: boneset, thoroughwort, Eupatorium perfoliatum
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

agueweed
    n 1: gentian of eastern North America having clusters of bristly
         blue flowers [syn: agueweed, ague weed, five-flowered
         gentian, stiff gentian, Gentianella quinquefolia,
         Gentiana quinquefolia]
    2: perennial herb of southeastern United States having white-
       rayed flower heads; formerly used as in folk medicine [syn:
       boneset, agueweed, thoroughwort, Eupatorium
       perfoliatum]