Source : Webster's Revised Unabridged Dictionary (1913)

Winter's bark \Win"ter's bark`\ (Bot.)
   The aromatic bark of tree ({Drimys, or Drymis, Winteri}) of
   the Magnolia family, which is found in Southern Chili. It was
   first used as a cure for scurvy by its discoverer, Captain
   John Winter, vice admiral to sir Francis Drake, in 1577.

Source : WordNet®

winter's bark
     n 1: aromatic bark having tonic and stimulant properties
     2: South American evergreen tree yielding winter's bark and a
        light soft wood similar to basswood [syn: {winter's bark
        tree}, {Drimys winteri}]