What beautiful but smelly tree has outlived its relatives and become an iconic species beloved across the world?
The Ginkgo biloba, also known as the “maidenhair tree.”
As the nickname suggests, the ginkgo is known for its beauty and unique leaf shape, which may look like a mane of unfurling golden hair when the tree makes its autumnal color change.
A Living Fossil
Famously, ginkgos have outlived the dinosaurs, and they haven’t changed much in recent times. There are fossil records dating back over 200 million years showing ginkgo relatives, and scientists have observed very few differences between those ancient precursors and the trees we see today.
The distinctive fan shape of their leaves isn’t found in any other tree species, and it makes this tree very easy to recognize. In fact, the ginkgo is the first tree name I learned because it’s so recognizable, and it has a special place in my heart for starting me on my plant-identification journey.
Alone in the World
Ginkgos, like all life, are distantly related to every other living plant and creature. However, we usually can observe many living relatives within a single genus, family, and order of life. (Remember, we categorize living organisms in a taxonomic system, from more general to more specific, using Kingdom, Phylum, Class, Order, Family, Genus, and Species). Ginkgo bilobais the only living species not just in its genus, but in its entire order, Ginkgoales.
They are native to China, but spread first across East Asia through trade, and then throughout the world. They can now be seen widely in Europe and the Americas, and are one example of a species whose cultivation by humans is inextricable from its story and its place in modern ecology.
Because of their hardiness, ginkgos have proliferated widely as humans introduced them beyond their native habitat. They do very well in urban environments, despite the challenges that exist for street trees like the lack of space for roots, soil compaction, and pollutants in the air and soil, so you can see them throughout cities all over the world.
In one extreme example, six ginkgos were among the survivors within 1-2 kilometers of the nuclear blast at Hiroshima, Japan in 1945. Though charred, the trees remained standing and returned to health, and went on to be marked by signs commemorating their feat. Talk about perseverance!
Besides such disasters, ginkgos can withstand regular pressures that trees face. It’s thought that their leaves are unattractive to pests, so they avoid pest problems that other tree species can suffer from. Though this may be good for the ginkgo, insects lose out in this equation. Unfortunately, these trees aren’t great champions of biodiversity, despite doing well for themselves.
Ginkgo trees can live to hundreds of years old without showing signs of decline and aging, and some ginkgos at temple sites are believed to be over 1500 years old.
What’s that smell?
Though I like to focus on the visual appeal of these trees, the leaves are not the only identifier that makes ginkgos stand out. They are also known for a particular rotten smell given off by their seed pods. Ginkgos have both male and female trees, but only the female trees drop such pungent pods. As a result, some landscapers in city streets and parks plant only the male trees to avoid the odorous issue.
One theory behind these stinky seed pods is that they evolved to be attractive to particular animals who would consume them and aid in their dispersal. A lot of trees and plants may be in a situation where the dispersal agents that once helped spread their seeds have gone extinct. However, humans themselves have lent a helping hand when it comes to spreading the ginkgo.
Medicinal, culinary, and cultural value
The ginkgo has long been used in traditional Chinese medicine to improve memory, slow aging, and invigorate blood flow. Though ginkgo products do circulate in the Western world for medicinal purposes, those come in the form of ginkgo extracts from the leaves, while traditional Chinese medicine primarily makes use of ginkgo seeds. There haven’t been definitive studies on their effectiveness, but regardless, people continue to value and consume ginkgo products.
The seed pods, which drop in autumn along with the leaves, can be collected and eaten, as long as you don’t eat them in very high quantities. The seeds contain a small amount of toxicity, so consuming large amounts can have adverse effects, and some folks have allergic reactions to the pods. However, the seeds are also used in a number of East Asian dishes, and can be quite delicious when you know what you’re doing.
When we come to value life forms as part of our cultures and our history, they stay by our side across lifetimes. If ginkgos can stick around from the time of the dinosaurs, who knows what they’ll go on to see?
May we all embody such resilience.
By Maya Dutta