Gardeners typically curse fall leaf drop, but ginkgo trees often get a pass, not only because the golden fall leaves look so great on the tree, but they also look great on the ground, not displaying the disheveled look of other larger tree leaves. Here’s our ginkgo tree, planted just in front of our office, that’s been putting on quite a show for the last few weeks.
Despite what most folks think, the genus Ginkgo is indeed a North American native, but to understand that, requires a bandwidth that many native plant purists simply don’t have. Native is not a place in location, it is only a place in time. The first Ginkgos date back to the lower Jurassic period about 190 million years ago, when the genus was born in Mongolia. From there, it migrated around the world, based on dramatic climate change, with fossils found from what is now the UK to the US (Oregon to North Dakota).
Ginkgos continued to diversify through the Cretaceous period (65-145 million years ago), when they reached their maximum distribution, with 5-6 species currently recognized. By the Paleocene (56-66 million years ago), all of the species but one had gone extinct. Although that remaining species is known as Ginkgo adiantoides, it is almost identical to today’s Ginkgo biloba.
During the Oligocene (23-34 million years ago), Ginkgos moved south from their more northerly range, with the genus completely disappearing from North America around 7 million years ago. According to the fossil records, Ginkgos subsequently disappeared from Europe around 2.5 million years ago. The only vestiges of the genus that remained, holed up in three distinct refugia (botanical hideouts) in China until humans began to spread them out again and re-populate the rest of the now Ginkgo-less world. They returned to the Flora of both North America and Europe in the 1700s.