  In the course of investigation of some interesting cosmic string universes in
the five dimensional Lyra manifold it is excitingly found that the geometry
itself of Lyra manifold behaves as a new source of dark energy and this energy
takes a form similar to that of quintessence in most of the cases, though in
one case the dark energy comes out to be that of the cosmological constant
type. The behaviour of the universes and their contribution to the process of
evolution are examined. Further study of such type of universes will be very
helpful in explaining the present accelerated expansion behaviour of the
universe.
