endosperm

from WordNet (r) 3.0 (2006)

endosperm
    n 1: nutritive tissue surrounding the embryo within seeds of
         flowering plants

from The Collaborative International Dictionary of English v.0.48

Endosperm \En"do*sperm\, n. [Endo- + Gr. ? seed.] (Bot.)
   The albumen of a seed; -- limited by recent writers to that
   formed within the embryo sac.
   [1913 Webster]