Source : Webster's Revised Unabridged Dictionary (1913)

Allogamy \Al*log"a*my\n. [Gr. ? other + ? marriage.] (Bot.)
   Fertilization of the pistil of a plant by pollen from another
   of the same species; cross-fertilization.

Source : WordNet®

allogamy
     n : cross-fertilization in plants [ant: {autogamy}]