Ginkgo biloba, commonly known asginkgo (/ˈɡɪŋkoʊ,ˈɡɪŋkɡoʊ/GINK-oh, -goh),[5][6] also known as themaidenhair tree,[7] and often misspelled "gingko" (seeEtymology below) is a species ofgymnosperm tree native toEast Asia. It is the last living species in the orderGinkgoales, which first appeared over 290 million years ago.Fossils similar to the living species, belonging to the genusGinkgo, extend back to theMiddle Jurassic epoch approximately 170 million years ago.[2] The tree was cultivated early inhuman history, remains commonly planted, and is widely regarded as aliving fossil.
G. biloba is a long-lived,disease-resistant,dioecious tree with unique fan-shapedleaves, capable ofclonal reproduction, and known for its striking yellow autumn foliage and resilience in disturbed environments. It was known historically as "silver fruit" or "white fruit" inChinese and called "ginkgo" due to a centuries-old transcription error. It is closely related tocycads and characterized by uniqueseeds that resembleapricots but are not truefruits.
G. biloba, once widespread but thoughtextinct in the wild for centuries, is now commonly cultivated in East Asia, with some genetically diverse populations possibly representing rare wild survivors insouthwestern China's mountainous regions. SomeG. biloba trees have survived extreme events like theHiroshima atomic bomb and others showcasing extreme longevity;G. biloba specimens have been measured in excess of 1,600 years, and the largest living trees are estimated to exceed 3,500 years.[8][9][10] Today it is widely planted incities worldwide for itspollution tolerance and ornamental value.
Ginkgos are large trees, normally reaching a height of 20–35 m (66–115 ft),[11] with some specimens in China being over 40 meters (131 feet).[12] The tree has an angularcrown 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. A combination of resistance to disease, insect-resistant wood, and the ability to formaerial roots and sprouts makes ginkgos durable, with some specimens estimated to be more than 3,500 years old.[13][14][15]
Theleaves are unique among seed plants, being fan-shaped with veins radiating out into the leaf blade, sometimes bifurcating (splitting), but neveranastomosing to form a network.[16] Two veins enter the leaf blade at the base and fork repeatedly in two; this is known asdichotomous venation. The leaves are usually 5–10 cm (2–4 in), but sometimes up to 15 cm (6 in) long. The old common name,maidenhair tree, derives from the leaves resemblingpinnae of the maidenhair fern,Adiantum capillus-veneris. Ginkgos are prized for their autumn foliage, which is a deepsaffron yellow.[17]
The species isheterophyllous (two types of leaves); those on the long shoots are thicker, have higher rates of photosynthesis, higher vein density and leaf hydraulic conductance, while those on the short shoots are better at handling drought.[18] Leaves of long shoots are also usually notched or lobed, but only from the outer surface, between the veins. They are borne both on the more rapidly growing branch tips, where they are alternate and spaced out, and also on the short, stubby spur shoots, where they are clustered at the tips. Leaves are green both on the top and bottom[19] and have stomata on both sides.[20] During autumn, the leaves turn a bright yellow and then fall, sometimes within a short space of time (one to fifteen days).[21] Leaves of thecultivar 'Tubifolia' have funnel-shaped leaves.[22]
Ginkgo branches grow in length by growth of shoots with regularly spaced leaves, as seen on most trees. From theaxils of these leaves, "spur shoots" (also known as short shoots) develop on second-year growth. Short shoots have shortinternodes (they may grow only one to two centimeters in several years) and their leaves are usually unlobed. They are short and knobby, and are arranged regularly on the branches except on first-year growth. Because of the short internodes, leaves appear to be clustered at the tips of short shoots, and reproductive structures are formed only on them (seeds and leaves are visible on short shoots). In ginkgos, as in other plants that possess them, short shoots allow the formation of new leaves in the older parts of the crown. After a number of years, a short shoot may change into a long (ordinary) shoot, or vice versa.[23]
G. biloba trunk cross-section
Ginkgo prefers full sun and grows best in environments that are well-watered and well-drained. The species shows a preference for disturbed sites; in the "semiwild" stands atTianmu Mountains, many specimens are found along stream banks, rocky slopes, and cliff edges. Accordingly, ginkgo retains a prodigious capacity for vegetative growth. It is capable of sprouting from embedded buds near the base of the trunk (lignotubers, or basal chichi) in response to disturbances, such as soil erosion. Old specimens are also capable of producing aerial roots on the undersides of large branches in response to disturbances such as crown damage; these roots can lead to successful clonal reproduction upon contacting the soil. These strategies are evidently important in the persistence of ginkgo; in a survey of the "semiwild" stands remaining inTianmushan, 40% of the specimens surveyed were multi-stemmed, and few saplings were present.[24]: 86–87
Ginkgo biloba isdioecious, with separatesexes, some trees beingfemale and others beingmale.[25] Male plants produce smallpollen cones withsporophylls, each bearing twomicrosporangia spirally arranged around a central axis. Sex conversion, wherein certain branches of a tree change sexes, has been observed.[26] This phenomenon is difficult to research because of its rarity, as well as the practice ofgrafting female branches onto otherwise male trees that was common in 19th century Europe.[27]
Female plants do not produce cones. Twoovules are formed at the end of a stalk, and afterwind pollination,[28] one or both develop intofruit-like structures containing seeds. The fruits are 1.5–2 cm long, with a soft, fleshy, yellow-brown outer layer (thesarcotesta) that is attractive in appearance, but containsbutyric acid[29] (also known as butanoic acid) and smells foul likerancidbutter orvomit[30] when fallen. Beneath the sarcotesta is the hardsclerotesta (the "shell" of the seed) and a paperyendotesta, with thenucellus surrounding the femalegametophyte at the center.[31]
Pollen cones
Ovules
The fertilization of ginkgo seeds occurs viamotile sperm, as in cycads, ferns, mosses, and algae. The sperm are large (about 70–90 micrometres)[32] and are similar to the sperm of cycads, which are slightly larger.Ginkgo sperm were first discovered by the Japanese botanistSakugoro Hirase in 1896.[33] The sperm have a complex multi-layered structure, which is a continuous belt of basal bodies that form the base of several thousand flagella which have a cilia-like motion. The flagella/cilia apparatus pulls the body of the sperm forwards. The sperm have only a tiny distance to travel to the archegonia, of which there are usually two or three. Two sperm are produced, one of which successfully fertilizes the ovule. Fertilization of ginkgo seeds occurs just before or after they fall in early autumn.[16][31] Embryos may develop in the seeds before or after they drop from the tree.[34]
Chinese scientists published a draftgenome ofGinkgo biloba in 2016.[35] The tree has a large genome of 10.6 billionDNAnucleobase "letters" (the human genome has three billion) and about 41,840 predictedgenes[36] which enable a considerable number of antibacterial and chemical defense mechanisms.[35] 76.58% of the assembled sequence turned out to be repetitive sequences.[37]
In 2020, a study in China of ginkgo trees up to 667 years old showed little effects of aging, finding that the trees continued to grow with age and displayed no genetic evidence ofsenescence, and continued to makephytochemicals indefinitely.[38]
Carl Linnaeus described the species in 1771, thespecific epithetbiloba derived from theLatinbis, "twice" andloba, "lobed", referring to the shape of the leaves.[42] Two names for the species recognise the botanistRichard Salisbury, a placement by Nelson asPterophyllus salisburiensis and the earlierSalisburia adiantifolia proposed byJames Edward Smith. The epithet of the latter may have been intended to denote a characteristic resemblingAdiantum, the genus of maidenhair ferns.[43]
The scientific nameGinkgo is the result of a spelling error that occurred three centuries ago.Kanji typically have multiple pronunciations in Japanese, and the characters 銀杏 used forginnan can also be pronouncedginkyō.Engelbert Kaempfer, the firstWesterner to investigate the species in 1690, wrote down this pronunciation in the notes that he later used for theAmoenitates Exoticae (1712) with the "awkward" spelling "ginkgo".[44] This appears to be a simple error of Kaempfer; taking his spelling of other Japanese words containing the syllable "kyō" into account, a more preciseromanization following his writing habits would have been "ginkio" or "ginkjo".[45] Linnaeus, who relied on Kaempfer when dealing with Japanese plants, adopted the spelling given in Kaempfer's "Flora Japonica" (Amoenitates Exoticae, p. 811). Kaempfer's drawing can be found in Hori's article.[46]
The relationship of ginkgo to other plant groups remains uncertain. It has been placed loosely in the divisionsSpermatophyta andPinophyta, but no consensus has been reached. Since its seeds are not protected by anovary wall, it can morphologically be considered agymnosperm. The apricot-like structures produced by female ginkgo trees are technically notfruits, but are seeds that have a shell consisting of a soft and fleshy section (thesarcotesta), and a hard section (thesclerotesta). The sarcotesta has a strong smell that most people find unpleasant.[47][48][49]
The ginkgo is classified in its owndivision, the Ginkgophyta, comprising the single class Ginkgoopsida, order Ginkgoales, familyGinkgoaceae, genusGinkgo and is the onlyextant species within this group. It is one of the best-known examples of aliving fossil, because Ginkgoales other thanG. biloba are not known from the fossil record after thePliocene.[50][51]
A digital recreation ofBaiera made from diverse images of fossils and academic descriptions
Ginkgo biloba is aliving fossil, with fossils recognisably related to modern ginkgo from the earlyPermian (Cisuralian), with likely oldest record being that ofTrichopitys from the earliest Permian (Asselian) of France, over 290 million years old.[53] The closest living relatives of theclade are thecycads,[24]: 84 which share with the extantG. biloba the characteristic ofmotile sperm.
Such plants with leaves that have more than fourveins per segment have customarily been assigned to the taxonGinkgo, while the taxonBaiera is used to classify those with fewer than four veins per segment.Sphenobaiera has been used for plants with a broadly wedge-shaped leaf that lacks a distinct leaf stem.[54][55]
The Ginkgophyta declined in diversity as the Cretaceous progressed, and by thePaleocene,Ginkgo adiantoides was the onlyGinkgo species left in theNorthern Hemisphere, while a markedly different (and poorly documented) form persisted in theSouthern Hemisphere. Along with that of ferns, cycads, and cycadeoids, the species diversity in the genusGinkgo drops through the Cretaceous, at the same time the flowering plants were on the rise; this supports the hypothesis that, over time, flowering plants with better adaptations to disturbance displacedGinkgo and its associates.[24]: 93
At the end of thePliocene,Ginkgo fossils disappeared from the fossil record everywhere except in a small area ofcentral China, where the modern species survived.
It is doubtful whether the Northern Hemisphere fossil species ofGinkgo can be reliably distinguished. Given the slow pace of evolution and morphological similarity between members of the genus, there may have been only one or two species existing in the Northern Hemisphere through the entirety of theCenozoic: present-dayG. biloba (includingG. adiantoides) andG. gardneri from thePaleocene ofScotland.[24]: 85
At least morphologically,G. gardneri and the Southern Hemisphere species are the only known post-Jurassic taxa that can be unequivocally recognised. The remainder may have beenecotypes orsubspecies. The implications would be thatG. biloba had occurred over an extremely wide range, had remarkable genetic flexibility and, thoughevolving genetically, never showed muchspeciation.[56][57]
While it may seem improbable that a single species may exist as a contiguous entity for many millions of years, many of the ginkgo's life-history parameters fit: Extreme longevity; slow reproduction rate; (in Cenozoic and later times) a wide, apparently contiguous, but steadily contracting distribution; and (as far as can be demonstrated from the fossil record) extreme ecological conservatism (restriction to disturbed streamside environments).[24]: 91
Given the slow rate of evolution of the genus,Ginkgo possibly represents a pre-angiosperm strategy for survival in disturbed streamside environments.Ginkgo evolved in an era before flowering plants, whenferns,cycads, andcycadeoids dominated disturbed streamside environments, forming low, open, shrubby canopies.Ginkgo's large seeds and habit of "bolting" – growing to a height of 10 meters before elongating its side branches – may be adaptations to such an environment.
Modern-dayG. biloba grows best in environments that are well-watered and drained,[24]: 87 and the extremely similar fossilGinkgo favored similar environments: The sediment record at the majority of fossilGinkgo localities indicates it grew primarily indisturbed environments, such as along streams.[24]Ginkgo, therefore, presents an "ecological paradox" because while it possesses some favorable traits for living in disturbed environments (clonal reproduction) many of its other life-history traits are the opposite of those exhibited by modern plants that thrive in disturbed settings (slow growth, large seed size, late reproductive maturity).[24]: 92
The older Chinese name for this plant is 銀果, meaning "silver fruit", pronouncedyínguǒ in Mandarin orNgan-gwo in Cantonese. The current commonly used names are 白果 (bái guǒ), meaning 'white fruit', and銀杏 (yínxìng), meaning 'silverapricot'. The name 銀杏 was translated intoJapanese as イチョウ (ichou) or ぎんなん (ginnan) and intoKorean as 은행 (eunhaeng). 銀杏 had been particular terminology used during theSong dynasty fortributary reasons in place of the then contemporary 鴨脚 ("duckfeet", from its leaves) in northeast China where it commonly grew.[58]
Despite its spelling, which is due to a complicated etymology including a transcription error, "ginkgo" is usually pronounced/ˈɡɪŋkoʊ/, which has given rise to the common alternative spelling "gingko". Thespelling pronunciation/ˈɡɪŋkɡoʊ/ is also documented in some dictionaries.[61][62]
Engelbert Kaempfer first introduced the spellingginkgo in his bookAmoenitatum Exoticarum of 1712.[63] It is considered that he may have misspelled "Ginkjo" or "Ginkio" (both consistent with his treatment of Japanesekyō in the same work) as "Ginkgo". This misspelling was included by Linnaeus in his bookMantissa plantarum II[64] and has become the name of the tree's genus.[45][61] The specific epithetbiloba is New Latin for "two-lobed".
AlthoughGinkgo biloba and other species of the genus were once widespread throughout the world, its habitat had shrunk by two million years ago.
For centuries, it was thought to be extinct in the wild,[65] but is now a common tree cultivated throughout eastern China, Korea, and Japan. Many municipalities in China, Korea and Japan use Ginkgos as street trees, and Ginkgo leaves are the emblem of prominent educational institutions such as theUniversity of Tokyo andSungkyunkwan University in South Korea. Despite their widespread habitat, highgenetic uniformity exists among ginkgo trees, with some Chinese scholars suggesting that ginkgo trees in these areas may have been planted and preserved by Chinese monks over about 1,000 years.[66] A study demonstrates a greater genetic diversity inSouthwestern China populations, supporting glacial refugia in mountains surrounding the easternTibetan Plateau, where several old-growth candidates for wild populations have been reported.[66][67] Whether native ginkgo populations still exist has not been demonstrated unequivocally, but there is genetic evidence that these Southwestern populations may be wild, as well as evidence that the largest and oldestG. biloba trees may be older than surrounding human settlements.[66]
Where it occurs in the wild, Ginkgo is found infrequently in deciduous forests and valleys on acidicloess (i.e. fine, silty soil) with good drainage. The soil it inhabits is typically in the pH range of 5.0 to 5.5.[68] While cultivated specimens can survive in a variety of environments (such as a subtropical climate),[69] the wild ginkgo is native to areas with a mostly temperate climate.[70]
Ginkgo has long been cultivated in China. It is common in the southern third of the country.[68] Some planted trees at temples are believed to be over 1,500 years old. The first record of Europeans encountering it is in 1690 inJapanese temple gardens, where the tree was seen by the German botanistEngelbert Kaempfer. Because of its status inBuddhism andConfucianism, the ginkgo has also been widely planted in Korea and in Japan since the 14th century;[71] in both areas, some naturalization has occurred, with ginkgos seeding into natural forests. Ginkgo has been commonly cultivated in North America for over 200 years and in Europe for close to 300, but during that time, it has never become significantlynaturalized.[72]
G. biloba is also commonly manually planted in cities across the United States and Europe. This species is highly tolerant to pollution and serves as a visually appealing, shade-providing tree in many cities and gardens.[73]
Many intentionally planted ginkgos are malecultivars grafted onto plants propagated from seed, because the male trees will not produce the malodorous seeds. The popular cultivar 'Autumn Gold' is a clone of a male plant.[74]
The disadvantage of maleGinkgo biloba trees is that their pollen is highly allergenic. They have an OPALS (Ogren Plant Allergy Scale) rating of 7 (out of 10), whereas female trees, which can produce nopollen, have an OPALS allergy scale rating of 2.[75]
Female cultivars include 'Liberty Splendor', 'Santa Cruz', and 'Golden Girl', the latter so named because of the striking yellow color of its leaves in the fall; all female cultivars release zero pollen.[75]
Ginkgos adapt well to the urban environment, tolerating pollution and confined soil spaces.[78] They rarely have disease problems, even in urban conditions, and are attacked by few insects.[79][80]
Ginkgos are popular subjects for growing as miniature landscapes known aspenjing andbonsai;[81] they can be kept artificially small and tended over centuries. The trees are easy to propagate from seed.
Extreme examples of the ginkgo's tenacity may be seen inHiroshima, Japan, where six trees growing between 1 and 2 kilometres (1⁄2 and1+1⁄4 miles) from the1945 atom bomb explosion were among the few livingorganisms in the area to survive the blast. Although almost all other plants (and animals) in the area were killed, the ginkgos, though charred, survived and were soon healthy again, among otherhibakujumoku (trees that survived the blast).[82]
The six trees are still alive: They are marked with signs at Housenbou (報専坊) temple (planted in 1850),Shukkei-en (planted about 1740), Jōsei-ji (planted 1900), at the former site of Senda Elementary School near Miyukibashi, at theMyōjōin temple, and anEdo period-cutting at Anraku-ji temple.[83]
The stump of the ancient fallen ginkgo which has produced new shoots in recent[when?] years
At theTsurugaoka Hachiman-gū's shrine in the city ofKamakura,Kanagawa Prefecture, Japan, an ancient ginkgo tree stands beside the stone entry staircase. According to legend, the tree has stood there since the founding of the shrine circa 1063.[84] The tree is nicknamedkakure-ichō (hiding ginkgo), because of anEdo period legend in whichshōgunMinamoto no Sanetomo was assassinated in 1219 by his nephew,Kugyō, who had hidden behind the tree to ambush the shōgun.[84]
Modern scholarship has established that ginkgos arrived from China in the 14th century, and a 1990 tree-ring measurement indicated thekakure-ichō's age to be about 500 years.[85]
On 10 March 2010, the tree blew down in a storm, but the stump has since sprouted vigorously.[84]
The grounds of the Buddhist temple at Gu Guanyin in theZhongnan Mountains feature a ginkgo tree reputed to be 1,400 years old.[86][87] The tree itself is a popular tourist attraction.
When eaten in large quantities or over a long period, the seeds may cause poisoning byginkgotoxin (4'-O-methylpyridoxine, MPN), as found in a fewcase reports.[89][90] A heat-stable compound not destroyed by cooking, MPN may cause convulsions, which were alleviated by treatment withpyridoxinephosphate (vitamin B6), according to limited studies.[89][90]
Some people are sensitive to the chemicals in thesarcotesta, the outer fleshy coating. These people should handle the seeds with care, wearing disposable gloves, when preparing them for consumption. The symptoms are allergic contactdermatitis,[91][92] orblisters similar to that caused by contact withpoison ivy.[93]
Ginkgopollen may produceallergic reactions.[39]Ginkgo biloba leaves andsarcotesta contain ginkgolic acids[96] – which are highlyallergenic – long-chain alkylphenols, such asbilobol oradipostatin A[97] (bilobol is a substance related toanacardic acid fromcashew nut shells andurushiols present inpoison ivy and otherToxicodendron spp.)[39][92] Individuals with a history of strong allergic reactions to poison ivy, mangoes, cashews and other alkylphenol-producing plants are more likely to experience an allergic reaction when consuming non-standardized ginkgo-containing preparations.[39] The level of these allergens in standardized pharmaceutical preparations fromGinkgo biloba was restricted to 5ppm by theCommission E of the former Federal German Health Authority. Overconsumption of seeds fromGinkgo biloba can depletevitamin B6.[98][99]
Close-up of Ginkgo tree bearing ripe, fruit-like sarcotestaeGinkgo 'seeds' (sclerotestae) with sarcotesta removedGinkgo seeds served with boiled coconut flesh as a dessert in Thailand
Despite the health risks in certain cases, the nut-like kernels of the seeds are esteemed in Asia, and are a traditional ingredient inChinese food. Ginkgo nuts are used incongee, and are often served at special occasions such as weddings and theChinese New Year (as part of the vegetarian dish calledBuddha's delight). Japanese cooks add ginkgo seeds (calledginnan) to dishes such aschawanmushi, and cooked seeds are often eaten along with other dishes. Grilled ginkgo nuts with salt are also a popular item atizakayas as a snack with beer and other Japanese food.[100] In Korea, ginkgo nuts are stir-fried and eaten, or are used to garnish foods such assinseonro.[101]
G. biloba and its extracts are notapproved as a drug in the United States and do not have sufficientclinical evidence for uses as a therapy, according to a 2023 review.[109] The United StatesNational Center for Complementary and Integrative Health concludes that despite extensive research, ginkgo has not been conclusively proved as effective for any health condition, including dementia, cognitive decline, or other disorders for which it is commonly marketed.[94]
A 2021 umbrella review concluded thatG. biloba may be useful and safe for improving cognitive function and daily living activities in people withAlzheimer's disease.[110] A 2018 review concluded that 22- to 24-week treatment with aG. biloba extract improved behavioral and psychological symptoms ofdementia, and reduced caregiver distress compared toplacebo.[111] A 2017 overview of systematic reviews concluded thatG. biloba extract may modestly improve cognitive function and daily living in dementia when taken at doses over 200 mg per day for at least 22 weeks.[112] A 2016 systematic review concluded thatG. biloba extract reducedtardive dyskinesia symptoms in people withschizophrenia and is generally safe.[113]
Over the period 2021-2023, the US FDA issuedwarning letters to manufacturers of ginkgodietary supplements for false advertising abouthealth claims and misbranding of their products as non-approved drugs.[115]
Ginkgo has been used intraditional Chinese medicine since at least the 11th century CE.[116] Ginkgo seeds, leaves, and nuts have traditionally been used to treat various ailments, such as dementia, asthma, bronchitis, and kidney and bladder disorders. However, there is no conclusive evidence that ginkgo is useful for any of these conditions.[39][94][117]
Symbol ofTokyo, Japan's capital, representing a ginkgo leaf
The ginkgo leaf is the symbol of theUrasenke school ofJapanese tea ceremony. The tree is the official tree of the Japanese capital ofTokyo, and the symbol of Tokyo is a ginkgo leaf. Since 1948, the badge ofTokyo University has been two ginkgo leaves (designed by Shoichi Hoshino), which became the university logo in 2004 with a redesign.[118] The logo ofOsaka University has been a simplified ginkgo leaf since 1991 when designerIkko Tanaka created it for the university's sixtieth anniversary.[119]
^abcdApproximate reconstructions by B. M. Begović Bego and Z. Zhou, 2010/2011. Source: B.M. Begović Bego, (2011). Nature's MiracleGinkgo biloba, Book 1, Vols. 1–2, pp. 60–61.
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^abSchötz K (2004). "Quantification of allergenic urushiols in extracts ofGinkgo biloba leaves, in simple one-step extracts and refined manufactured material (EGb 761)".Phytochemical Analysis.15 (1):1–8.Bibcode:2004PChAn..15....1S.doi:10.1002/pca.733.PMID14979519.
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^Crane PR (2013).Ginkgo: The Tree That Time Forgot. New Haven: Yale University Press. p. 242.ISBN978-0-300-21382-9.According to some sources, the medicinal use of ginkgo dates back to 2800 B.C.… However, the first undisputed written records of ginkgo come much later… Ginkgo first appears in copies of the Shen Nung pharmacopeia around the eleventh and twelfth centuries.
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![Extinct Ginkgo yimaensis[52]](/mt/?noimg=&dark=on&url=https%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aGinkgo_yimaensis.jpg)
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![Extinct Ginkgo adiantoides, or possibly a new US taxon, G. cranei[52]](/mt/?noimg=&dark=on&url=https%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aGinkgo_cranei.jpg)
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