On the matroids in which all hyperplanes are binary

In this paper, it is shown that, for a minor-closed class M of matroids, the class of matroids in which every hyperplane is in M is itself minor-closed and has, as its excluded minors, the matroids U1.1 ⊛ N such that N is an excluded minor for M. This result is applied to the class of matroids of the title, and several alternative characterizations of the last class are given.