The Collaborative International Dictionary of English v.0.48:

decumary \decumary\ n.
   a woody climber of southeastern US (Decumaria barbara)
   having white flowers in compound terminal clusters.

   Syn: Decumaria barbata, Decumaria barbara.
        [WordNet 1.5] Decumbence

WordNet (r) 3.0 (2006):

decumary
    n 1: woody climber of southeastern United States having white
         flowers in compound terminal clusters [syn: decumary,
         Decumaria barbata, Decumaria barbara]