Source : Webster's Revised Unabridged Dictionary (1913)

   {Down tree} (Bot.), a tree of Central America ({Ochroma
      Lagopus}), the seeds of which are enveloped in vegetable
      wool.

Source : WordNet®

Ochroma lagopus
     n : forest tree of lowland Central America having a strong very
         light wood; used for making floats and rafts and in
         crafts [syn: {balsa}]