The Collaborative International Dictionary of English v.0.48:

applemint \applemint\ n.
   1. a mint (Mentha rotundifolia or Mentha suaveolens) with
      apple-scented stems of South and West Europe; naturalized
      in U.S.

   Syn: apple mint.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Mentha rotundifolia
    n 1: mint with apple-scented stems of southern and western
         Europe; naturalized in United States [syn: apple mint,
         applemint, Mentha rotundifolia, Mentha suaveolens]