Ginkgo is a genus of highly unusual non-flowering plants. The scientific name is also used as the English name. The order to which it belongs, Ginkgoales, first appeared in the Permian, 250 million years ago, possibly derived from "seed ferns" of the order Peltaspermales. The rate of evolution within the genus has been slow, and almost all its species had become extinct by the end of the Pliocene; the exception is the sole living species, Ginkgo biloba, which is only found in the wild in China, but is cultivated across the world. The relationships between ginkgos and other groups of plants are not fully resolved.