The Collaborative International Dictionary of English v.0.48:

Botany \Bot"a*ny\, n.; pl. Botanies. [F. botanique, a. & n.,
   fr. Gr. ? botanic, fr. ? herb, plant, fr. ? to feed, graze.]
   1. The science which treats of the structure of plants, the
      functions of their parts, their places of growth, their
      classification, and the terms which are employed in their
      description and denomination. See Plant.
      [1913 Webster]

   2. A book which treats of the science of botany.
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   Note: Botany is divided into various departments; as,

   Structural Botany, which investigates the structure and
      organic composition of plants;

   Physiological Botany, the study of their functions and
      life; and

   Systematic Botany, which has to do with their
      classification, description, nomenclature, etc.
      [1913 Webster]