  Quiver Grassmannians are projective varieties parametrizing
subrepresentations of given dimension in a quiver representation. We define a
class of quiver Grassmannians generalizing those which realize degenerate flag
varieties. We show that each irreducible component of the quiver Grassmannians
in question is isomorphic to a Schubert variety. We give an explicit
description of the set of irreducible components, identify all the Schubert
varieties arising, and compute the Poincar\'e polynomials of these quiver
Grassmannians.
