  The Grassmann convexity conjecture gives a conjectural formula for the
maximal total number of real zeros of the consecutive Wronskians of an
arbitrary fundamental solution to a disconjugate linear ordinary differential
equation with real time. The conjecture can be reformulated in terms of convex
curves in the nilpotent lower triangular group. The formula has already been
shown to be a correct lower bound and to give a correct upper bound in several
small dimensional cases. In this paper we obtain a general explicit upper
bound.
