Source : Webster's Revised Unabridged Dictionary (1913)

Herbal \Herb"al\, a.
   Of or pertaining to herbs. --Quarles.

Herbal \Herb"al\, n.
   1. A book containing the names and descriptions of plants.
      --Bacon.

   2. A collection of specimens of plants, dried and preserved;
      a hortus siccus; an herbarium. --Steele.

Source : WordNet®

herbal
     adj : of or relating to herbs; "herbal tea, herbal medicine"