The Collaborative International Dictionary of English v.0.48:

Water tupelo \Wa"ter tu"pe*lo\ (w[add]"t[~e]r
   t[=u]"p[-e]*l[=o]). (Bot.)
   A species of large tupelo (Nyssa aquatica) growing in
   swamps in the southern of the United States. See Ogeechee
   lime.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Nyssa aquatica
    n 1: columnar swamp tree of southeastern to midwestern North
         America yielding pale soft easily worked wood [syn: water
         gum, Nyssa aquatica]