  The description of irreducible representations of a group G can be seen as a
question in harmonic analysis; namely, decomposing a suitable space of
functions on G into irreducibles for the action of G x G by left and right
multiplication.
  For a split p-adic reductive group G over a local non-archimedean field,
unramified irreducible smooth representations are in bijection with semisimple
conjugacy classes in the ``Langlands dual'' group.
  We generalize this description to an arbitrary spherical variety X of G as
follows: Irreducible unramified quotients of the space $C_c^\infty(X)$ are in
natural ``almost bijection'' with a number of copies of $A_X^*/W_X$, the
quotient of a complex torus by the ``little Weyl group'' of X. This leads to a
description of the Hecke module of unramified vectors (a weak analog of
geometric results of Gaitsgory and Nadler), and an understanding of the
phenomenon that representations ``distinguished'' by certain subgroups are
functorial lifts. In the course of the proof, rationality properties of
spherical varieties are examined and a new interpretation is given for the
action, defined by F. Knop, of the Weyl group on the set of Borel orbits.
