Source : Webster's Revised Unabridged Dictionary (1913)

Bladderwort \Blad"der*wort`\, n. (Bot.)
   A genus ({Utricularia}) of aquatic or marshy plants, which
   usually bear numerous vesicles in the divisions of the
   leaves. These serve as traps for minute animals. See
   {Ascidium}.

Source : WordNet®

bladderwort
     n : any of numerous aquatic carnivorous plants of the genus
         Utricularia some of whose leaves are modified as small
         urn-shaped bladders that trap minute aquatic animals