The Collaborative International Dictionary of English v.0.48:

Amsonia \Amsonia\ n.
   1. 1 a genus of herbs and subshrubs with milky juice and
      showy bluish flowers; native from Europe to Asia Minor to
      Japan and North America.

   Syn: genus Amsonia.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Amsonia
    n 1: genus of herbs and subshrubs with milky juice and showy
         bluish flowers; Europe to Asia Minor to Japan and North
         America [syn: Amsonia, genus Amsonia]