adders-tongue

from The Collaborative International Dictionary of English v.0.48

Adder's-tongue \Ad"der's-tongue`\, n. (Bot.)
   (a) A genus of ferns ({Ophioglossum}), whose seeds are
       produced on a spike resembling a serpent's tongue.
   (b) The yellow dogtooth violet. --Gray.
       [1913 Webster]