The ginkgo tree is an ancient tree with no close living relatives. Only one species exists today, (Ginkgo biloba), although fossils of species related to G. biloba can be found going back as far as 270 million years, to the Permian geologic period. Thus the ginkgo is considered to be a "living fossil."
G. biloba is native to China, but there is controversy over whether any wild populations of the ginkgo tree still exist. Some groves of trees have been tended and preserved by Chinese monks for over 1000 years.
The tree is very hardy and disease-resistant, and is often cultivated in the U.S., Europe, and Asia. Besides reproducing from seeds, ginkgo trees can also reproduce vegetatively from root-like structures that grow from the base of the trunk and spread. This alternate form of reproduction may help explain the extraordinary persistence of G. biloba throughout geologic time.
Ginkgo leaf extract has a reputation for improving memory and concentration by increasing blood flow to the brain. Some studies support this claim, but other studies refute it and show no effect. Clinical trials are underway investigating whether this herb can help prevent the onset of dementia and Alzheimer's disease, as well as other diseases and disorders.