WordNet (r) 3.0 (2006):

subdivision Ginkgophyta
    n 1: ginkgos: in some systems classified as a class and in
         others as a subdivision; used in some classifications for
         one of five subdivisions of Gymnospermophyta [syn:
         Ginkgopsida, class Ginkgopsida, Ginkgophytina, class
         Ginkgophytina, subdivision Ginkgophytina, subdivision
         Ginkgophyta]