Ginkgo is a group of seed plants that do not produce flowers. These plants are classified as gymnosperms. The scientific name for this group is also its common English name. The order Ginkgoales, which includes the Ginkgo genus, first appeared during the Permian period, about 270 million years ago. Today, Ginkgo is the only living genus in this order. The evolution of this group has been very slow, and most of its species became extinct by the end of the Pliocene epoch. The only species that survives today, Ginkgo biloba, is found naturally only in China but is grown in many places around the world. Scientists are still studying how ginkgos are related to other types of plants.

Although ginkgo is often used as a traditional medicine or supplement, there is no strong scientific evidence that it helps prevent or treat diseases.

Evolution

Trichopitys heteromorpha from the earliest Permian period in France is one of the oldest fossils linked to the Ginkgophyta group. It had leaves that split into many parts, with thin, thread-like ends. Sphenobaiera (early Permian–Cretaceous) had wedge-shaped leaves that split into narrow sections with two veins, but no leaf stalks. Baiera (Triassic–Jurassic) had similar leaves but with leaf stalks.

The living ginkgo (Ginkgo biloba) is a living fossil. Fossils similar to modern ginkgo date back to the Permian period, about 270 million years ago. The ancestor of the ginkgo genus is thought to have separated from other gymnosperms around 325 million years ago. The last common ancestor of today’s only surviving ginkgo species lived no earlier than 390,000 years ago. The closest living relatives of ginkgo are cycads.

The time when ginkgo separated from other plants is estimated to be extremely ancient, dating to the early Carboniferous period. Fossils of ginkgo with reproductive parts like modern ginkgo first appeared in the Middle Jurassic period. The genus spread widely across Laurasia during the Jurassic and Early Cretaceous periods. By the end of the Pliocene, ginkgo fossils disappeared globally except in a small area of central China, where the modern species survived. It is uncertain whether Northern Hemisphere ginkgo fossils can be reliably identified. Because ginkgo evolved slowly and its members look similar, there may have been only one or two species in the Northern Hemisphere throughout the Cenozoic era: present-day G. biloba (including G. adiantoides) and G. gardneri from the Palaeocene of Scotland.

At least morphologically, G. gardneri and Southern Hemisphere ginkgo species are the only post-Jurassic ginkgo fossils that can be clearly recognized. Other fossils may have been ecotypes or subspecies. This suggests that G. biloba once lived in a very large area, had strong genetic adaptability, and evolved slowly without creating many new species. Though it seems unlikely for a species to exist unchanged for millions of years, ginkgo’s traits support this. It lives a long time, reproduces slowly, and its habitat has gradually shrunk. Fossil records show that ginkgo lived in disturbed streamside environments.

Modern Ginkgo biloba grows best in well-watered and well-drained soil. Similar conditions are shown in fossil records, which indicate that ancient ginkgo also lived near streams and levees. Ginkgo is ecologically unusual because, while it can reproduce through cloning (which helps in disturbed areas), it also has traits like slow growth, large seeds, and late reproduction that are uncommon in plants that thrive in disturbed environments.

Because ginkgo evolved slowly, it may represent an older survival strategy from before flowering plants existed. Ginkgo evolved when ferns, cycads, and cycadeoids dominated disturbed streamside environments. Its large seeds and growth pattern—reaching about 10 meters (30 feet) before growing side branches—may be adaptations to this environment. Ginkgo diversity decreased during the Cretaceous period, along with ferns, cycads, and cycadeoids, as flowering plants became more common. This supports the idea that flowering plants, better adapted to disturbed environments, replaced ginkgo and its relatives over time.

As of 2013, molecular studies showed at least six different ways to classify ginkgo relative to cycads, conifers, gnetophytes, and angiosperms. The two most common are that ginkgo is closely related to a group of conifers and gnetophytes, or that ginkgo and cycads form a group within gymnosperms. A 2013 study found the strongest support for ginkgo and cycads being a single group:

Pinaceae (the pine family)

Cupressophytes (other conifers)

The German naturalist Engelbert Kaempfer introduced the spelling "ginkgo" in his 1712 book Amenitatum Exoticarum, using it from a Japanese manuscript by Tekisai Nakamura. He may have misspelled the Japanese word "ginkyo" or "ginkio," which means "silver apricot" in Chinese characters. The original Chinese name, "silver apricot," appeared in Chinese herbology texts like the 1329 Daily Use Materia Medica and the 1578 Compendium of Materia Medica. It refers to the shape of the leaves, described as "duckfeet" in 11th-century Song dynasty writings.

The genus Ginkgo was officially named by Carl Linnaeus in his 1771 book Mantissa plantarum II. He used Kaempfer’s spelling for the genus name. Though spelled "ginkgo," it is usually pronounced /ˈɡɪŋkoʊ/, leading to the alternative spelling "gingko." Some dictionaries note the pronunciation /ˈɡɪŋkɡoʊ/.

The Ginkgoaceae family was first described by Adolf Engler in 1897. It contains only the genus Ginkgo. The name is a nomen conservandum, meaning it is kept despite breaking some botanical naming rules.

Human uses

Ginkgo seeds, leaves, and nuts have been used in traditional Chinese medicine since at least the 11th century AD to treat various health issues. However, there is no scientific proof that ginkgo is effective for treating diseases or improving health. Although ginkgo is often sold as a dietary supplement, it has not been shown to provide any proven health benefits.

Ginkgolides are chemicals found in ginkgo leaves. These chemicals are a type of compound made from a structure with 20 carbon atoms, created through a process involving a substance called geranylgeranyl pyrophosphate. Ginkgo leaves contain many different plant chemicals, including flavonoids such as quercetin, kaempferol, and isorhamnetin. Ginkgo seeds contain carbohydrates, protein, and fats. They are also covered with butyric acid and caproic acid, which cause a strong, unpleasant smell.

In Korea, the soft part of ginkgo seeds is sometimes eaten with rice.

The ginkgo tree has appeared in art and culture in both East Asia and the Western world. In Japan, ginkgo leaves are shown in woodblock prints, such as those by Utamaro depicting a woman named Ofuji, known as "Miss Ginkgo." Ginkgo leaves also appear in the chonmage hairstyle worn by sumo wrestlers.

In the Western world, ginkgo leaves were used as a design in Art Nouveau art at the beginning of the 20th century. This style was popular in France, where ginkgo leaves were carved into stone and used in metalwork in the city of Nancy.

In professional sumo wrestling, athletes in the top two divisions (jūryō and makuuchi) wear a special hairstyle called ōichōmage. This hairstyle is shaped like a ginkgo leaf and is named after the tree.