The ginkgo, 200 million years old and all its branches
Discover, every day, an analysis of our partner The Conversation. Today, two biodiversity researchers tell us the story of one of the oldest trees on the planet
- Ginkgo has exceptional longevity - more than 1,000 years, some writings even indicate 3,000 years - according to a study published by our partner The Conversation.
- Frequently planted all over the world, ginkgo is originally a tree native to the mountains of southern China.
- This "biography" of ginkgo was conducted by Serge Muller, professor, a researcher at the Institute of Systematics - Evolution - Biodiversity of the National Museum of Natural History and Germinal Rouhan, lecturer, systematic botanist, a researcher at the Institute of systematic - evolution - biodiversity of the National Museum of Natural History.
Much like welwitschia, Chinese redwood, and Wollemi pine, ginkgo belongs to the group of gymnosperms, the seeds of which are often protected in cones, as is the case with firs and spruces. Gymnosperms, unlike sophoras or catalpas, for example, are therefore not flowering plants (called angiosperms ).
The diversity of gymnosperms was highest in the Mesozoic (-250 to -66 million years ago) before dropping sharply. Only about a thousand species remain today, especially widespread in the boreal and mountainous regions.
Certain lineages of gymnosperms are no longer represented by one or a few species, often considered as “relics” of these ancient groups. The Ginkgo biloba, a venerable tree survivor of the primary era, is one of those "relics species."
How to recognize ginkgo?
Ginkgo ( Ginkgo biloba L.) is the only current representative of the Ginkgoaceae family and the order of Ginkgoales. It is easily recognized by its fan-shaped leaves which are often bilobed, which gave the species its name, Biloba.In the fall, its deciduous foliage takes on a beautiful golden yellow hue before falling. It is a beautiful looking tree, with a very characteristic habit, which can reach 30 to 40 m in height in France.
Catkins on a male tree (left) and ova on a female tree (right) © Marcin Kolasiński / Serge Muller - CC BY-NC-ND
It is a dioecious species: the male and female organs are carried by different trees. Male trees form cylindrical catkins on short twigs; female trees produce ovoid-shaped ova on peduncles. At the Jardin des Plantes in Paris is a male tree onto which a branch of a female individual has been successfully grafted.
How it was "discovered"
Ginkgo is well known because it is very frequently planted all over the world. So much so that one would forget that it is a tree native to the mountains of southern China. It must be said that its natural stands have long been sought, in vain. It was only recently, in 2012, that the ginkgo trees in the natural habitats of Dalou Mountain (China) were characterized as a relict natural population of the species.
From its natural relict populations, the species was first introduced to other regions of China, then to Japan and Korea from the 12th century by Buddhist monks; this explains why one can find in these countries trees that are nearly 1000 years old, especially near Shinto shrines.
Ginkgo leaves © Schnobby / Wikimedia - CC BY-NC-SA
It is from these populations naturalized in Japan that the species was introduced into Europe. The German naturalist Engelbert Kaempfer, who stayed in Japan from 1690 to 1692, was the first European who described this tree in 1712 in his memoir Amoenitatum exoticarum.
Young ginkgo shoots were brought to Holland by his successors from the Dutch East India Company and it is in the botanical garden of Utrecht that the first European ginkgo will be planted in 1730. It was then introduced to the botanical garden of Kew ( London) in 1761, then in the botanical garden of Montpellier in 1778 by its director Antoine Gouan, from plants received from the Montpellier naturalist physician Auguste Broussonet from the English botanist Sir Joseph Banks. Gouan made a description of the species and illustrated it.
A resistant tree with exceptional longevity
Ginkgo has many unusual characteristics. It has exceptional longevity - over 1000 years, some writings even indicate 3,000 years; longevity explained in a recent scientific publication by specific molecular mechanisms against aging. The species also has effective defense systems against many pathogenic organisms.
It is a tree that resists drought well and thus appears well adapted to climate change. Ginkgo is also resistant to air pollution and is among the first species that redeveloped after the atomic bomb explosion in Hiroshima.
But it is the relict natural populations of ginkgo trees from Dalou Mountain (China) that deserve above all the implementation of conservation measures. These populations include trees over 800 years old, but the species is rare and endangered, which is why it is considered endangered. Conservation measures, hopefully effective, of these refuge stations, have been put in place.
Where to see ginkgo trees?
Ginkgo is now widely used as an ornamental tree in French parks and gardens, as in many other countries. Usually, male trees are planted in cities because in female trees the outer wall of the ova gives off butyric acid with a strong and unpleasant smell of rancid butter.
The Opendata of the city of Paris thus reports nearly a thousand trees of this species distributed in the streets and parks of the capital, in particular in the 13th arrondissement (avenue d'Italie in particular). For Bordeaux, 136 trees are mapped on the city's Opendata.
In 1989, during the bicentenary of the French Revolution, the 514 municipalities of Seine-et-Marne chose to plant a ginkgo tree as a symbol of freedom. A website has even been created to map the remarkable trees planted in France.
The ginkgo trees at Saint-Sulpice-Laurière (Haute-Vienne) station, as well as that of the town hall park in Toul (Meurthe-et-Moselle), received the “ Remarkable Tree of France ”label in 2001 and 2015. The city of Strasbourg is also proud of the presence of four majestic ginkgo trees, offered in 1880 by the Emperor of Japan to the German Emperor William II, and planted on the Place de la République.
“Ginkgos Biloba, the invincible trees” © StrasTV / Youtube 2017
It is certainly in Japan that the species is the most popular, the most remarkable trees being classified there as natural monuments. The ginkgo leaf has been the stylized symbol of the city of Tokyo since 1989. The species is particularly popular in the fall when it is adorned with golden hues.
The German poet JW von Goethe, who also had a great admiration for ginkgo planted in 1795 at Heidelberg Castle, devoted a poem there addressed in 1815 to his friend Marianne von Willemer, accompanied by two leaves of the tree ... This tree- there unfortunately no longer exists.
A "panchronic" tree
The ginkgo is considered a panchronic tree, once called a "living fossil" by Darwin. This expression is incorrect and should be abandoned, although it is still sometimes used in publications relating to ginkgo. A fossil of course cannot be alive!
But above all, the notion of "living fossil" implies that the conservation of the overall appearance of a species would be due to a lack of evolution, while any species continues to evolve, each at its own pace, this rhythm being vary over time. It remains nonetheless true that the current ginkgo is the only and last representative of a family ( Ginkgoaceae, the oldest family of current trees), of an order (the Ginkgoales ) and even of a class ( the Ginkgopsida ), which already existed in the Paleozoic (or primary era), there are 265 million years.
Paleontological studies show that the genus Ginkgo included several species in the Jurassic (-205 to -135 million years ago) and that it reached a peak of diversity in the Cretaceous (-135 to -66 million years ago) where, throughout the northern hemisphere, many species are represented, including Ginkgo adiantoides present from the Upper Cretaceous to the Miocene, and very close to G. Biloba by the shape of its leaves and the structure of its ova.
This analysis was written by Serge Muller, professor, a researcher at the Institute of Systematics - Evolution - Biodiversity, and Germinal Rouhan, Senior Lecturer, Systematic Botanist, Researcher at the Institute of Systematics - Evolution - Biodiversity (both at the Muséum national of natural history).
The original article was published on the Conversation website.