A minimal area problem imposing different length conditions on open and
closed curves is shown to define a one parameter family of covariant
open-closed quantum string field theories. These interpolate from a recently
proposed factorizable open-closed theory up to an extended version of Witten's
open string field theory capable of incorporating on shell closed strings. The
string diagrams of the latter define a new decomposition of the moduli spaces
of Riemann surfaces with punctures and boundaries based on quadratic
differentials with both first order and second order poles.Comment: 12 pages, 7 figures (not included