The Collaborative International Dictionary of English v.0.48:

Dutchman's-pipe \Dutchman's-pipe\ n.
   a hardy deciduous American vine (Aristolochia durior)
   having large, heart-shaped leaves and bearing brownish-purple
   flowers which have their calyx tubes curved like the bowl of
   a tobacco pipe. Formerly classified as Aristolochia Sipho.

   Syn: pipe vine, Aristolochia macrophylla, Aristolochia
        durior.
        [1913 Webster + WordNet 1.5]

WordNet (r) 3.0 (2006):

Aristolochia durior
    n 1: hardy deciduous vine having large leaves and flowers with
         the calyx tube curved like the bowl of a pipe [syn:
         Dutchman's-pipe, pipe vine, Aristolochia macrophylla,
         Aristolochia durior]