^BGinkgo tree.^b View of branches and leaves of a maidenhair tree (^IGinkgo biloba)^i in autumn colours. This tree is the only living representative of the family ^IGinkgoaceae^i. The two-lobed leaf is unique among trees in having no midrib and having a branching fan of veins from the base of the leaf. The golden yellow colouration in autumn is due to the degradation of the chlorophyll present in the leaves. ^IGinkgo biloba^i has separate male and female plants. The tree was sacred in Ancient China, and has since been introduced around the world. ^IGinkgo^i extract is used in herbal medicine for many purposes, including to enhance memory.