The Collaborative International Dictionary of English v.0.48:

fingerroot \fingerroot\ n.
   tall leafy European biennial or perennial (Digitalis
   purpurea) having spectacular clusters of large tubular
   pink-purple flowers; -- its leaves yield the drug digitalis
   and are poisonous to livestock.

   Syn: common foxglove, fairy bell, fingerflower, Digitalis
        purpurea.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

finger-root
    n 1: tall leafy European biennial or perennial having
         spectacular clusters of large tubular pink-purple flowers;
         leaves yield drug digitalis and are poisonous to livestock
         [syn: common foxglove, fairy bell, fingerflower,
         finger-flower, fingerroot, finger-root, Digitalis
         purpurea]