  The most general large N eigenvalues distribution for the one matrix model is
shown to consist of tree-like structures in the complex plane. For the m=2
critical point, such a split solution describes the strong coupling phase of 2d
quantum gravity (c=0 non-critical string). It is obtained by taking
combinations of complex contours in the matrix integral, and the relative
weight of the contours is identified with the non-perturbative theta-parameter
that fixes uniquely the solution of the string equation (Painleve I). This
allows to recover by instanton methods results on the non-perturbative effects
obtained by the Isomonodromic Deformation Method, and to construct for each
theta-vacuum the observables (the loop correlation functions) which satisfy the
loop equations. The breakdown of analyticity of the large N solution is related
to the existence of poles for the loop operators.
