Definition of: hymenium

(hī·mē′nē·əm) noun plural ·ni·a (-nē·ə) or ·ni·ums Bot.
The fruit–bearing surface or stratum in the higher fungi of the Ascomycetes or Basidiomycetes, as the two vertical faces on the gills of the common mushroom. It consists of a collection of basidia, sometimes interspersed with sterile cells in a layer or stratum. [<NL <Gk. hymenion, dim. of hymen membrane]