Ginkgo biloba, known as ginkgo, also spelled gingko, or as the maidenhair tree, is the only living species in the division Ginkgophyta, all others being extinct. It is found in fossils dating back 270 million years. Native to China, the tree is widely cultivated and was introduced early to human history. It has various uses in traditional medicine and as a source of food. The genus name Ginkgo is regarded as a misspelling of the Japanese gin kyo, "silver apricot". Ginkgos are large trees, normally reaching a height of 20-35 m (66-115 ft), with some specimens in China being over 50 m (160 ft). The tree has an angular crown and long, somewhat erratic branches, and is usually deep rooted and resistant to wind and snow damage. Young trees are often tall and slender, and sparsely branched; the crown becomes broader as the tree ages. During autumn, the leaves turn a bright yellow, then fall, sometimes within a short space of time (one to 15 days). A combination of resistance to disease, insect-resistant wood and the ability to form aerial roots and sprouts makes ginkgos long-lived, with some specimens claimed to be more than 2,500 years old.