Source : Webster's Revised Unabridged Dictionary (1913)

Runch \Runch\, n. (Bot.)
   The wild radish. --Dr. Prior.

Source : WordNet®

runch
     n : Eurasian weed having yellow or mauve or white flowers and
         podlike fruits [syn: {jointed charlock}, {wild radish}, {wild
         rape}, {Raphanus raphanistrum}]