Daily our headlines give us horror stories of more species sent to extinction by the destructive activities of humans. But did you know that one tree species at least, the Ginko, has enjoyed the reverse experience?
Ginko are described as living fossils, believed to have been around for 270 million years, since the beginning of the dinosaurs, or even prior. Modern Ginko’s ancestors are even likely to be the first species of what we think of as a tree – the Ginko family is the evolutionary link between ferns and conifers. Ginko has an almost frond-like leaf, hence its old common name of Maiden-Hair Tree after the domesticated ornamental fern. Ginko is deciduous, turning a beautiful golden yellow in autumn before dropping all its leaves in one shot. But Ginko is not a flowering tree, rather it belongs to the more primitive group of non-flowering trees that we normally associate with pines, cedars, spruces, and other conifers with needle-like foliage and cones rather than flowers. Only one species of Ginko survives, and it is so unique that botanists now classify it in its very own Order (within which it has its own Family and within that its own Genus).
There are believed to have been many species of Ginko in the distant past that covered a large part of the northern hemisphere, but by about 2 million years ago they were reduced to just a few species in China. Ginko produces delicious nuts which are likely to have been eaten by dinosaurs who then distributed the seeds, much like the role of birds (dinosaur remnants) in modern ecosystems. Demise of the dinosaurs about 65 million years ago, now thought likely due to catastrophic climate change initiated by a giant meteor strike, is a possible cause of the concurrent demise of Ginko.
Ginko is now believed to likely be extinct in the wild, unable to compete with faster growing, more aggressive and better adapted modern conifers and flowering plants that squeeze it out of its preferred habitat – disturbed sites. But thanks to Budha, Chinese monks since ancient times have been propagating Ginko and it is a popular temple ground specimen because of its beautiful autumn colours, delicious nuts, and therapeutic properties. The eldest living Ginko is believed to be about 3,500 years old (so actually pre-dates Budha). Ginko was brought to Korea and Japan along with Budhism, and stunning ancient specimens also adorn temples in these two countries.
But in a huge irony, Ginko, whilst unable to survive in nature, seems almost designed to live in modern human cities. Its insect repellent wood means it is untroubled by borers and grazers. Ginko shows a high tolerance to air pollution and global warming (higher atmospheric CO2 levels), and incredibly, even radiation. Six Ginko trees with 2km of the 1945 Hiroshima atomic blast still thrive today and are almost the only living things within that zone to have done so. Tea brewed from Ginko leaves is even thought to be effective in treating that most modern of human epidemics – depression. Did the wonderful Ginko line up a future survival partnership with our species 270 million years prior to our existence?