The Collaborative International Dictionary of English v.0.48:

Water pore \Wa"ter pore`\,
   1. (Zool.) A pore by which the water tubes of various
      invertebrates open externally.
      [1913 Webster]

   2. (Bot.) One of certain minute pores in the leaves of some
      plants. They are without true guardian cells, but in other
      respects closely resemble ordinary stomata. --Goodale.
      [1913 Webster]

WordNet (r) 3.0 (2006):

water pore
    n 1: a pore that exudes water on the surface or margin of a leaf
         of higher plants [syn: hydathode, water pore, water
         stoma]