Why is the ginkgo tree sometimes called a living fossil?
Ginkgo tree is included in division Ginkgophyta (as a gymnosperm).
It is the only surviving member of the division. The leaf morphology is typical, and hence the scientific name is Ginkgo biloba .
Surprisingly, same leaves are found in fossilised form, from 270 million years old Permian bed. In fact the plant was initially known to scientific community of Europe only as fossils; a German naturalist recognised the trees in a Japanese temple garden in 1691 and brought some seeds to botanical garden of Utrecht.
Subsequently the plant was classified and became known as a 'living fossil' as it hasn't changed since more than 250 million years.