Trees

Abstract

The effects of glaciation described above by Good were much less severe for China. If the idyllic sequence of which he writes, though perhaps modified, persisted there, it can help explain how for some species that country served as a place of last refuge. Ginkgo biloba, a gymnosperm, for example, is the sole survivor there of a genus formerly widespread in the world and with an immensely long fossil history dating back nearly 200 million years. Seward (1938) charts the decline of the gingkophytes — the close relatives of Ginkgo. By the beginning of the Oligocene only 2 out of 19 genera remained. The decline continued into the Miocene and they disappeared in the Americas. In Europe Ginkgo appears to have survived into the Pliocene and then succumbed to the effects of glaciation. Wilson (1929) attributed its survival in China to protection in Buddhist monastery gardens, but this appears to be unfounded. What are surely more relevant are the benign effects of having escaped the ravages of glaciation.

“All the available evidence points to the fact that the Flowering Plants, from the time they are first recognised... right down to the middle or end of the Pliocene, pursued the even tenor of their way... their history seems to have been that of .. broadening and differentiating by the multiplication of forms. Then quite rapidly... during the Pliocene this idyllic sequence was broken by a drastic deterioration in the climates of higher latitudes, culminating in widespread glaciation and presenting to the world of Flowering Plants problems of environmental harmony which it had never before encountered”.

Good (1964)