Ginkgo biloba

Ginkgo biloba, commonly known asginkgoorgingko(/ˈɡɪŋkoʊ,ˈɡɪŋkɡoʊ/GINK-oh, -⁠goh),also known as themaidenhair tree,is a species ofgymnospermtree native toEast Asia. It is the last living species in the orderGinkgoales, which first appeared over 290 million years ago, and fossils very similar to the living species, belonging to the genusGinkgo, extend back to theMiddle Jurassicepoch approximately 170 million years ago.The tree was cultivated early inhuman historyand remains commonly planted, and is widely regarded as aliving fossil.
The plant may betoxicorallergenicin certain cases. Leafextractis commonly used as adietary supplement, but there is insufficientclinical evidencethat it supports human health or is effective against any disease.
Ginkgos are large trees, normally reaching a height of 20–35 m (66–115 ft),with some specimens in China being over 50 m (165 ft). The tree has an angularcrownand 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 rootsand sprouts makes ginkgos durable, with some specimens claimed to be more than 2,500 years old.
Theleavesare unique among seed plants, being fan-shaped with veins radiating out into the leaf blade, sometimes bifurcating (splitting), but neveranastomosingto form a network.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 resemblingpinnaeof the maidenhair fern,Adiantum capillus-veneris. Ginkgos are prized for their autumn foliage, which is a deepsaffron yellow.
Leaves of long shoots are 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 bottomand have stomata on both sides.During autumn, the leaves turn a bright yellow and then fall, sometimes within a short space of time (one to fifteen days).Leaves of the variety or formaG. b. tubifoliahave funnel-shaped leaves.
Ginkgo branches grow in length by growth of shoots with regularly spaced leaves, as seen on most trees. From theaxilsof 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.
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.
Ginkgo bilobaisdioecious, with separatesexes, some trees beingfemaleand others beingmale.Male plants produce smallpollen coneswithsporophylls, each bearing twomicrosporangiaspirally arranged around a central axis. Sex conversion, wherein certain branches of a tree change sexes, has been observed.This phenomenon is difficult to research because of its rarity as well as the practice of grafting female branches onto otherwise male trees that was common in 19th century Europe.
Female plants do not produce cones. Twoovulesare formed at the end of a stalk, and afterwind pollination,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(also known as butanoic acid) and smells foul likerancidbutterorvomitwhen fallen. Beneath the sarcotesta is the hardsclerotesta(the "shell" of the seed) and a paperyendotesta, with thenucellussurrounding the femalegametophyteat the center.
The fertilization of ginkgo seeds occurs viamotilesperm, as in cycads, ferns, mosses, and algae. The sperm are large (about 70–90 micrometres)and are similar to the sperm of cycads, which are slightly larger.Ginkgosperm were first discovered by the Japanese botanistSakugoro Hirasein 1896.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.Embryos may develop in the seeds before or after they drop from the tree.
Chinese scientists published a draftgenomeofGinkgo bilobain 2016.The tree has a large genome of 10.6 billionDNAnucleobase"letters" (the human genome has three billion) and about 41,840 predictedgeneswhich enable a considerable number of antibacterial and chemical defense mechanisms.76.58% of the assembled sequence turned out to be repetitive sequences.
In 2020, a study in China ofginkgotrees 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 makephytochemicalsindefinitely.
Extracts of ginkgo leaves containphenolic acids,proanthocyanidins,flavonoid glycosides, such asmyricetin,kaempferol,isorhamnetin, andquercetin, and theterpenetrilactonesginkgolidesandbilobalides.The leaves also contain unique ginkgobiflavones,alkylphenols, andpolyprenols.
The older Chinese name for this plant is 銀果, meaning "silver fruit", pronouncedyínguǒin Mandarin orNgan-gwoin 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 intoJapaneseas イチョウ (ichou) or ぎんなん (ginnan) and intoKoreanas 은행 (eunhaeng).
Carl Linnaeusdescribed the species in 1771, thespecific epithetbilobaderived from theLatinbis, "twice" andloba, "lobed", referring to the shape of the leaves.Two names for the species recognise the botanistRichard Salisbury, a placement by Nelson asPterophyllus salisburiensisand the earlierSalisburia adiantifoliaproposed byJames Edward Smith. The epithet of the latter may have been intended to denote a characteristic resemblingAdiantum, the genus of maidenhair ferns.
The scientific nameGinkgois the result of a spelling error that occurred three centuries ago.Kanjitypically have multiple pronunciations in Japanese, and the characters 銀杏 used forginnancan also be pronouncedginkyō.Engelbert Kaempfer, the firstWesternerto 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".This appears to be a simple error of Kaempfer; taking his spelling of other Japanese words containing the syllable "kyō" into account, a more preciseromanizationfollowing his writing habits would have been "ginkio" or "ginkjo".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.
The relationship of ginkgo to other plant groups remains uncertain. It has been placed loosely in the divisionsSpermatophytaandPinophyta, but no consensus has been reached. Since its seeds are not protected by anovarywall, 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.
The ginkgo is classified in its owndivision, the Ginkgophyta, comprising the single class Ginkgoopsida, order Ginkgoales, familyGinkgoaceae, genusGinkgoand is the onlyextant specieswithin this group. It is one of the best-known examples of aliving fossil, because Ginkgoales other thanG. bilobaare not known from the fossil record after thePliocene.
Ginkgo bilobais aliving fossil, with fossils recognisably related to modern ginkgo from the earlyPermian(Cisuralian), with likely oldest record being that ofTrichopitysfrom the earliest Permian (Asselian) of France, over 290 million years old.The closest living relatives of thecladeare thecycads,which share with the extantG. bilobathe characteristic ofmotilesperm.
Such plants with leaves that have more than fourveinsper segment have customarily been assigned to the taxonGinkgo, while the taxonBaierais used to classify those with fewer than four veins per segment.Sphenobaierahas been used for plants with a broadly wedge-shaped leaf that lacks a distinct leaf stem.
Fossils attributable to the genusGinkgofirst appeared in theMiddle Jurassic. The genusGinkgodiversified and spread throughoutLaurasiaduring theJurassicandEarly Cretaceous.
The Ginkgophyta declined in diversity as the Cretaceous progressed, and by thePaleocene,Ginkgo adiantoideswas the onlyGinkgospecies 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 genusGinkgodrops 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 displacedGinkgoand its associates.
At the end of thePliocene,Ginkgofossils 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 ofGinkgocan 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. gardnerifrom thePaleoceneofScotland.
At least morphologically,G. gardneriand the Southern Hemisphere species are the only known post-Jurassic taxa that can be unequivocally recognised. The remainder may have beenecotypesorsubspecies. The implications would be thatG. bilobahad occurred over an extremely wide range, had remarkable genetic flexibility and, thoughevolvinggenetically, never showed muchspeciation.
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).
Given the slow rate of evolution of the genus,Ginkgopossibly represents a pre-angiospermstrategy for survival in disturbed streamside environments.Ginkgoevolved in an era before flowering plants, whenferns,cycads, andcycadeoidsdominated disturbed streamside environments, forming low, open, shrubby canopies.Ginkgo'slarge 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. bilobagrows best in environments that are well-watered and drained,and the extremely similar fossilGinkgofavored similar environments: The sediment record at the majority of fossilGinkgolocalities indicates it grew primarily indisturbed environments, such as along streams.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).
The genus name is regarded as a misspelling of theJapanese pronunciationgin kyō([ɡiŋkʲoː]) for thekanji銀杏meaning "silverapricot",which is found inChinese herbologyliterature such as日用本草(Daily UseMateria Medica) (1329) andCompendium of Materia Medica本草綱目published in 1578.
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.
Engelbert Kaempferfirst introduced the spellingginkgoin his bookAmoenitatum Exoticarumof 1712.It is considered that he may have misspelled "Ginkjo" or "Ginkio" (both consistent with his treatment of Japanesekyōin the same work) as "Ginkgo". This misspelling was included by Linnaeus in his bookMantissa plantarum IIand has become the name of the tree's genus.The specific epithetbilobais New Latin for "two-lobed".
AlthoughGinkgo bilobaand 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,but is now a common tree cultivated throughout eastern China, Korea, and Japan. Many municipalities in Korea and Japan use Ginkgos as street trees, and Ginkgo leaves are the emblem of prominent educational institutions such as theUniversity of TokyoandSungkyunkwan Universityin South Korea. Despite their widespread habitat, highgenetic uniformityexists 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.A study demonstrates a greater genetic diversity inSouthwestern Chinapopulations, supporting glacial refugia in mountains surrounding the easternTibetan Plateau, where several old-growth candidates for wild populations have been reported.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. bilobatrees may be older than surrounding human settlements.
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.
Ginkgo has long been cultivated in China. It is common in the southern third of the country.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 inBuddhismandConfucianism, the ginkgo has also been widely planted in Korea and in Japan since the 14th century;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.
G. bilobais 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.
Many intentionally planted ginkgos are malecultivarsgrafted 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.
The disadvantage of maleGinkgo bilobatrees is that they are 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.
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.
Many cultivars are listed in the literature in theUK, of which the compact 'Troll' has gained theRoyal Horticultural Society'sAward of Garden Merit.
Ginkgos adapt well to the urban environment, tolerating pollution and confined soil spaces.They rarely have disease problems, even in urban conditions, and are attacked by few insects.
Ginkgos are popular subjects for growing as miniature landscapes known aspenjingandbonsai;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 between1 and 2 kilometres (1⁄2and1+1⁄4miles) from the1945 atom bomb explosionwere among the few livingorganismsin 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).
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 atAnraku-jitemple.
At theTsurugaoka Hachiman-gū'sshrine 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.The tree is nicknamedkakure-ichō(hiding ginkgo), because of anEdo periodlegend in whichshōgunMinamoto no Sanetomowas assassinated in 1219 by his nephew,Kugyō, who had hidden behind the tree to ambush the shōgun.
Modern scholarship has established that ginkgos arrived from China in the 14th century, and a 1990 tree-ring measurement indicated thekakure-ichō'sage to be about 500 years.
On 10 March 2010, the tree blew down in a storm, but the stump has since sprouted vigorously.
The grounds of the Buddhist temple at Gu Guanyin in theZhongnan Mountainsfeature a ginkgo tree reputed to be 1,400 years old.The tree itself is a popular tourist attraction.
Since 2016,G. bilobaextract is classified as a possible humancarcinogen(group 2B) by theInternational Agency for Research on Cancer.
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.A heat-stable compound not destroyed by cooking, MPN may cause convulsions, which were alleviated by treatment withpyridoxinephosphate(vitamin B6), according to limited studies.
Some people are sensitive to the chemicals in thesarcotesta, the outer fleshy coating. These people should handle the seeds with care when preparing the seeds for consumption, wearing disposable gloves. The symptoms are allergic contactdermatitis,orblisterssimilar to that caused by contact withpoison ivy.
Side effectsof using ginkgo supplements may include increased risk of bleeding,gastrointestinal discomfort,nausea,vomiting,diarrhea, headaches, dizziness, heartpalpitations, and restlessness.Although use ofstandardizedGinkgo bilobaleaf extracts in moderate amounts appears to be safe,excessive use may have undesirable effects, especially in terms ofdrug interactions.The dosing ofanticoagulants, such aswarfarinor antiplatelet medication, may be adversely affected by using ginkgo supplements.
According to asystemic review, the effects of ginkgo onpregnantwomen may include increasedbleeding time, and there is inadequate information about safety duringlactation.
Ginkgopollenmay produceallergic reactions.Ginkgo bilobaleaves andsarcotestacontain ginkgolic acids– which are highlyallergenic– long-chain alkylphenols, such asbiloboloradipostatin A(bilobol is a substance related toanacardic acidfromcashew nutshells andurushiolspresent inpoison ivyand otherToxicodendronspp.)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.The level of these allergens in standardized pharmaceutical preparations fromGinkgo bilobawas restricted to 5ppmby theCommission Eof the former Federal German Health Authority. Overconsumption of seeds fromGinkgo bilobacan depletevitamin B6.
The wood ofGinkgo bilobais used to make furniture, chessboards, carving, and casks for makingsaké; the wood is fire-resistant and slow to decay.
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 atizakayasas a healthy snack with beer and other Japanese food.In Korea, ginkgo nuts are stir-fried and eaten, or are used to garnish foods such assinseonro.
AlthoughextractsofGinkgo bilobaleaf are often marketed as cognitive enhancers, there is no evidence for effects on memory or attention in healthy people.Systematic reviewshave shown there is no evidence for effectiveness of ginkgo in treatinghigh blood pressure,menopause-related cognitive decline,tinnitus,post-strokerecovery,oraltitude sickness.
There is weak preliminary evidence for ginkgo affectingdementiaandtardive dyskinesiasymptoms in people withschizophrenia.
Ginkgo has been used intraditional Chinese medicinesince at least the 11th century CE.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.
TheEuropean Medicines AgencyCommittee on Herbal Medicinal Productsconcluded that medicines containing ginkgo leaf can be used for treating mild age-relateddementiaand mildperipheral vascular diseasein adults after serious conditions have been excluded by a physician.
The ginkgo leaf is the symbol of theUrasenkeschool 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 Universityhas been two ginkgo leaves (designed by Shoichi Hoshino), which became the university logo in 2004 with a redesign.The logo ofOsaka Universityhas been a simplified ginkgo leaf since 1991 when designerIkko Tanakacreated it for the university's sixtieth anniversary.
In professionalsumo, wrestlers ranked in the two highest divisions (jūryōandmakuuchi) wear an elaboratetopknotcalledōichōmage(大銀杏髷,lit.'ginkgo-leaf topknot')because it resembles the leaf of the ginkgo tree.
Ginkgo is an official tree ofSeoulsince 1971, designated by theSeoul Metropolitan Government.