GINKGO or MAIDENHAIR TREE (Ginkgo biloba), a remarkable tree grown since ancient times about temples in China where it is considered a sacred plant. Although reported as native in western China, it is not positively known to occur in a truly wild state. It is a smooth, sparingly branched tree, sometimes 120 ft. high, with deciduous leaves, 2 to 4 in. broad and only about I in. long, which in form, veining and aspect resemble those of the maidenhair fern (q.v.). Botanically, the closest allies of the ginkgo are the cycads. As the sole survivor of a numerous group of plants with a very long geological ancestry the ginkgo may be legitimately regarded as a "living fossil." It has existed essen tially unchanged for perhaps ten million years, or probably for a longer period than any other living tree. Fossil species occur in the Carboniferous, Permian, Triassic, Jurassic and Tertiary f or mations in the British Isles, and forms with leaves very similar to those of the living ginkgo are abundant in Triassic and Jurassic rocks of the Pacific coast of North America, especially in Oregon and Alaska. The ginkgo is cultivated as an ornamental tree in temperate countries, growing without protection in many parts of Europe and also in North America as far north as the Great Lakes. (For its structural peculiarities see GYMNOSPERMS : Ginkgoales, Cycadales.)