Ginkgo biloba, a remarkable tree for several reasons!

by Gilles Vincent M.C., C.Q. | Member of the Canadensis Botanical Garden Society

There is no doubt that Ginkgo biloba, commonly known as “Maidenhair tree”, is the most fascinating tree in the plant world! Whether by its origin, its history, its long relationship with humans, its taxonomic status, the unique shape of its leaves or even its medicinal properties, no other representative of the approximately 60,000 trees known on the planet can compare to it.

Ginkgo biloba belongs to the Ginkgoaceae family, the only species in this family.  It can reach up to thirty meters and its lifespan is very long: there is even a specimen over 2,000 years old in Japan at Tohoku University in Sendai (Miyagi Prefecture). It is a species that is called “panchronic”, meaning that the current species presents many similarities with fossil species related to it! According to Sir Peter Crane, former director of Kew Garden and Ginkgo specialist, this tree is a living fossil.  Ginkgo fossils, dating back more than 200 million years, have been found on all continents of the northern hemisphere, which means that it even lived alongside the dinosaurs, which disappeared some 65 million years ago.

The resilience of Ginkgo is beyond doubt.  A specimen of this tree, located less than a kilometre from the epicentre of the catastrophic bombing of Hiroshima in August 1945, survived and has today become a monument that is almost sacred to the Japanese nation (Picture 1).

Picture 1. Ginkgo biloba having survived the bombing of Hiroshima in August 1945. Source:  jeremytreehugger / wordpress.com.

In addition, it could be considered a potentially immortal living being since it has no known diseases or parasites, no predators other than human activity. These characteristics probably explain why it is a popular street tree, particularly in Europe and Asia.

Following exhaustive studies of Ginkgo fossils, it is now accepted that the centre of origin of this tree is located in southeastern China. (see map).  Widely cultivated for its medicinal properties in China for thousands of years, it was introduced to the rest of Asia, notably Japan and Korea.  The first person to describe and identify it as Ginkgo was the German physician and naturalist Engelbert Kaempfer (1651-1716) during one of his many botanical explorations in Japan in the mid-17th century.  But it was the famous Swedish naturalist, Carl von Linné (1707-1778), considered the father of modern taxonomy by proposing a system of binomial nomenclature based on the name of genus and species, who added the epithet specific biloba about a century later.

Map1.
Localities where two colonies of Ginkgo biloba, possibly natives, were found. Jinfoshan (Municipality of Chongqing) and Tianmushan, (Zhejiang Province). Modified from Crane, 2013.

For those interested in trees, it is very easy to recognize the Ginkgo, particularly because of its architecture and its very particular crown. Although not very common in North America, we find them here and there in parks, on private land or along streets. However, it is found on the Red List of the International Union for Conservation of Nature (IUCN) with the mention “threatened species on a global scale”.  The reason is very simple since there are only two places where you can observe the Ginkgo in the wild. These two sites are located in China: in the Jinfo Mountain (administrative region of the municipality of Chongqing) and another in the Tianmushan mountain range (Zhejiang Province), located a few hours’ drive from Shanghai.

I had the great privilege of carrying out a few botanical excursions in the Tianmushan Nature Reserve, created in 1996, where I was able to observe one of these two indigenous stations (Photo 2).  I must admit, it was with a lot of emotion, on each of these excursions, that I found myself in the heart of this Ginkgo colony. This is the work of teams of researchers from Chinese universities, Shanghai Normal University and Zhejiang Normal University, who, through studies on the genetic diversity of several Ginkgo populations in China and elsewhere in Asia, were able to conclude that these two populations could very well be native or natural, both having shown particularly high genetic diversity.

Photo 2. The possibly original colony of Ginkgo biloba from the Tianmushan Nature Reserve, Zhejiang Province, China. Photo: Gilles Vincent.

The medicinal properties of Ginkgo are multiple! According to several sources, the use of Ginkgo in Chinese pharmacopoeia dates back more than 2,800 years (Crane, 2013).  We may think that it is the great longevity of Ginkgo, their resilience and their status as a resistant tree, which explains why its medicinal properties are often associated with longevity and health. Its ovules, which are often wrongly referred to as fruits and which are carried only by female trees, are widely consumed by the Chinese. It was very common to see local residents harvesting them in parks in China in the fall before they decompose, giving off a particularly nauseating odour.

Although many of the medicinal properties of Ginkgo have not been scientifically demonstrated, its leaves are rich in antioxidant compounds. Traditional Chinese medicine always has surprises in store for us, which is often difficult for us Westerners to take seriously.  Note that the importance of Ginkgo biloba in Asia is such that many universities on this continent have a Ginkgo leaf in their respective logo.

Whether by its particular habit, its fascinating history or the unique bright yellow colour the leaves take on in the fall (Photo 3), Ginkgo biloba has always been one of my two favourite trees, the other being Metasequoia glyptostroboides (Sichuan Metasequoia), also native to central China and placed on the list of threatened plants worldwide.  In Canada, the hardiness zone of Ginkgo biloba is “4b” and it could therefore be planted much more frequently in the Ottawa region and delight nature lovers of ornamental trees.

Photo 3. The unique bright yellow leaves of the Ginkgo biloba in the fall. Source: www.jardinage.lemonde.fr

Bibliographic source: Crane, P. (2013) Ginkgo, the tree that time forgot, Yale University Press, 384p.

—30—