Source : Webster's Revised Unabridged Dictionary (1913)

Pneumatophore \Pneu*mat"o*phore\, n. [Pneumato- + Gr. ? to
   bear.] (Zo["o]l.)
   One of the Pneumonophora.

Source : WordNet®

pneumatophore
     n : an air-filled root (submerged or exposed) that can function
         as a respiratory organ of a marsh or swamp plant