Source : Webster's Revised Unabridged Dictionary (1913)

Water celery \Wa"ter cel"er*y\ (Bot.)
   A very acrid herb ({Ranunculus sceleratus}) growing in
   ditches and wet places; -- called also {cursed crowfoot}.

Source : WordNet®

Ranunculus sceleratus
     n : annual herb growing in marshy places [syn: {cursed crowfoot},
          {celery-leaved buttercup}]