The Ginkgo biloba also known in English as the maindenhair tree is one of the living fossils that we can encounter almost every day.
Ginkgo biloba trees are commonly planted as ornamental trees. People seldom realize that Ginkgo trees are more ancient than one would immediately realize and in fact they represent a much older form of tree than even pines trees. Some form of Ginkgo trees, very much like the Ginkgo biloba tree of today have been around some 270 millions of years — or to put it another way a long time since before the dinosaurs have ever roamed the Earth.
The seeds of the Ginkgo biloba tree are only produced by the female tree and they look like fruit with their fleshy outer coating but they are anatomically very different from real fruits. The hard seed which looks like a nut once the soft parts are cleaned off is edible although it does contain Ginkgotoxin and can be dangerous.
The fruity Ginkgo seed have another negative effect when they start falling from ornamental trees planted in urban areas covering the sidewalks with a stinking slippery mess as they slowly rot away. Having to deal with them is by no means pleasant.
The leaves of the Ginkgo biloba tree also contain some minor amount of Ginkgotoxin but they are unlikely to cause a serious poisoning. Various extracts usually made from the leaves of the Ginkgo biloba are used for medicinal purposes to prevent or cure a variety of conditions and claimed to increase blood to the brain although it is not very clear how good the evidence is to prove that. Ginkgo biloba consumption can also have various unwanted side effects — even beyond the possibility of poisoning — so exercise extreme caution if you are considering taking Ginkgo biloba as a dietary supplement.
Further Readings:
Ginkgotoxin on Wikipedia.
Ginkgo Biloba Trees – Pictures, Facts on about.com.
GINKGO BILOBA-The Ginkgo Pages-The tree.