As the autumnal weather sets in, leaf colour is turning and the fan-shaped leaves of the maidenhair tree (Ginkgo biloba) are beginning to take on their striking butter yellow.   Sidmouth has a few ginkgo trees of varying sizes with the largest I’ve noticed on Woolbrook and Alexandria Roads. You’ll find smaller ones on Cotmaton Road and at the Knowle, quite close to the burnt out building. The youngest are in various places in the Byes.

150 million years ago there were many different ginkgo species and they were common across Europe, however with the ice ages of around 65m years ago the ginkgos all but died out.  A small pocket of the last remaining ginkgo species survived in south eastern China and has remained largely unchanged for those 65 million years. This has lead to it being described as a ‘living fossil’. 

It’s thanks to human activity that the ginkgo has increased its range, once again growing across the globe, having been planted for commerce and pleasure.  It was introduced to Britain in 1754 and thanks to its resistance to pollution, ginkgo is widely planted in cities.  

Ginkgo trees are dioecious which means they are either male or female.  The fruit of the female produces a very unpleasant vomit-like smell so, unsurprisingly, the male plant is more usually grown.  Ginkgos are long-lived and live for up to 4000 years, remaining fertile for over 1000 years. 

Gingko leaf has only recently been used in Western herbal medicine, originating from research undertaken in 1960s Germany into the leaf’s beneficial effects on the circulation.  Its history of medicinal use in traditional Chinese medicine dates back many centuries and in their tradition the fruit (or seed as it is more correctly known) was the plant part used, mainly for treating lung conditions.

The leaves contain many medicinally active constituents, including flavonoids, diterpenes and sesquiterpenes; these constituents both relax and dilate the blood vessels whilst also reducing the viscosity/stickiness of the blood.  This results in improved circulation to the brain and the arms and legs, and, consequently an improvement in conditions (such as dementia) when associated with impaired blood flow.   This combination of herbal actions is also helpful in the treatment of asthma.

Going a little deeper into how ginkgo affects our biochemistry, it is known to stimulate a pathway in the body known as the Nrf2 pathway, and it does that by gently irritating the surface of the cells.  Once activated the Nrf2 pathway stimulates the cell to strengthen and protect itself and also to increase its detoxification activity.  This may be one of the mechanisms by which gingko has a protective effect on the brain and also of improving energy metabolism. This medicinal tree is of immense value in the prevention and treatment of age-related vascular diseases too.  

Although ginkgo is generally regarded as safe, it must be used with care when in combination with certain medications and as such it’s best not to self-prescribe.

Keep an eye out for ginkgo’s butter yellow leaves over the next month before the October winds pull them from the trees.