Elaphrium tomentosum

from The Collaborative International Dictionary of English v.0.48

Tacamahac \Tac"a*ma*hac`\, Tacamahaca \Tac`a*ma*ha"ca\, n.
   1. A bitter balsamic resin obtained from tropical American
      trees of the genus {Elaphrium} ({Elaphrium tomentosum} and
      {Elaphrium Tacamahaca}), and also from East Indian trees
      of the genus {Calophyllum}; also, the resinous exhudation
      of the balsam poplar.
      [1913 Webster]

   2. (Bot.) Any tree yielding tacamahac resin, especially, in
      North America, the balsam poplar, or balm of Gilead
      ({Populus balsamifera}).
      [1913 Webster]