Source : Webster's Revised Unabridged Dictionary (1913)

Snake's-head \Snake's"-head`\, n. (Bot.)
   The Guinea-hen flower; -- so called in England because its
   spotted petals resemble the scales of a snake's head. --Dr.
   Prior.

   {Snake's-head iris} (Bot.), an iridaceous plant
      ({Hermodactylus tuberosus}) of the Mediterranean region.
      The flowers slightly resemble a serpent's open mouth.