Ginkgo biloba, also known as the maidenhair tree, and commonly known as ginkgo is a species of tree native to China. It is the only living species in the order Ginkgoales, which first appeared more than 290 million years ago. It is thought to be the oldest tree on the planet. The ginkgo leaves are used to treat poor circulation and maintain healthy blood flow to the central nervous system. It is also valuable for asthma and other allergy issues.