The Collaborative International Dictionary of English v.0.48:

Pharmacognosis \Phar`ma*cog*no"sis\, n. [Gr. fa`rmakon a drug +
   gnw^sis a knowing.]
   That branch of pharmacology which treats of unprepared
   medicines or simples; -- usually called pharmacognosy, and
   also pharmacography, and pharmacomathy.
   [1913 Webster]