The direct or indirect effect of male parent (pollen grain) on structures inside embryo sac except embryo has been termed by Focke, 1881 as xenia. This phenomenon is limited to endosperm part only and is seen in Zea mays. Metaxenia may be defined as the effect of pollen on the seed coat or pericarp lying outside the embryo sac. In Phoenix dactylifera, the size and time of maturity of fruits depend on the type of pollen grains fertilising the ovules. There is secretion of certain hormones or similar substances by endosperm or embryo or both which diffuse out into the wall of the seed and fruit and exert specific effect. The secretion of these substances, in turn, is influenced by the pollen grains which fertilise the ovules.