  In planar QCD, in two space time dimensions, the meson eigenvalue equation
has a nonlocal structure interpretable as resulting from hidden degrees of
freedom. The nonlocality can be reconstructed from the functional form of the
pion mass dependence on quark mass within an expansion starting from a special
one dimensional Schroedinger problem. The one dimensional problem makes the
pion mass depend on the quark mass through a simple quadratic relation which is
shown to be compatible also with numerical data obtained in four dimensions.
