''Ginkgo'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of non-flowering

seed plants A spermatophyte (; ), also known as phanerogam (taxon Phanerogamae) or phaenogam (taxon Phaenogamae), is any plant that produces seeds, hence the alternative name seed plant. Spermatophytes are a subset of the embryophytes or land plants. They inc ...

. The scientific name is also used as the English name. The order to which it belongs, Ginkgoales, first appeared in the

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last ...

, 270 million years ago, and is now the only living genus within the order. The rate of evolution within the genus has been slow, and almost all its species had become extinct by the end of the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Ginkgo biloba ''Ginkgo biloba'', commonly known as ginkgo or gingko ( ), also known as the maidenhair tree, is a species of tree native to China. It is the last living species in the order Ginkgoales, which first appeared over 290 million years ago. Fossil ...

'' is only found in the wild in China, but is cultivated around the world. The relationships between ginkgos and other groups of plants are not fully resolved.

Prehistory

The ginkgo (''Ginkgo biloba'') is a

living fossil A living fossil is an extant taxon that cosmetically resembles related species known only from the fossil record. To be considered a living fossil, the fossil species must be old relative to the time of origin of the extant clade. Living foss ...

, with fossils similar to the modern plant dating back to the

, 270 million years ago. The closest living relatives of the clade are the

cycad Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male o ...

s, which share with the extant ''G. biloba'' the characteristic of

motile Motility is the ability of an organism to move independently, using metabolic energy. Definitions Motility, the ability of an organism to move independently, using metabolic energy, can be contrasted with sessility, the state of organisms th ...

sperm. The ginkgo and cycad lineages are thought to have an extremely ancient divergence dating to the early Carboniferous. Fossils attributable to the genus ''Ginkgo'' with reproductive organs similar to the modern species first appeared in the Middle Jurassic, and the genus diversified and spread throughout Laurasia during the

Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...

and Early Cretaceous. It declined in diversity as the Cretaceous progressed with the extinction of species such as '' Ginkgo huolinhensis'', and by the Palaeocene, only a few ''Ginkgo'' species, ''

Ginkgo cranei ''Ginkgo cranei'' is an extinct ''Ginkgo'' species in the family Ginkgoaceae described from a series of isolated fossil ovulate organs and leaves. The species is known from upper Paleocene sediments exposed in the state of North Dakota, USA. ...

'' and ''

Ginkgo adiantoides ''Ginkgo adiantoides'' is an extinct ginkgo species in the family Ginkgoaceae from the Late Cretaceous to the Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by ...

'', remained in the Northern Hemisphere, while a markedly different (and poorly documented) form persisted in the Southern Hemisphere. At the end of the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Cenozoic: present-day ''G. biloba'' (including ''G. adiantoides'') and '' G. gardneri'' from the Palaeocene of

Scotland Scotland (, ) is a Countries of the United Kingdom, country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a Anglo-Scottish border, border with England to the southeast ...

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 been

ecotype In evolutionary ecology, an ecotype,Greek: ''οίκος'' = home and ''τύπος'' = type, coined by Göte Turesson in 1922 sometimes called ecospecies, describes a genetically distinct geographic variety, population, or race within a specie ...

s or subspecies. The implications would be that ''G. biloba'' had occurred over an extremely wide range, had remarkable genetic flexibility and, though

evolving Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation t ...

genetically, never showed much speciation. While it may seem improbable that a species may exist as a contiguous entity for many millions of years, many of the ginkgo's life-history parameters fit. These are: extreme longevity; slow reproduction rate; (in Cenozoic and later times) a wide, apparently contiguous, but steadily contracting distribution coupled with, as far as can be demonstrated from the fossil record, extreme ecological conservatism (restriction to disturbed streamside environments). Royer et al. (2003), p. 91. Modern-day ''G. biloba'' grows best in well-watered and drained environments, and the extremely similar fossil ''Ginkgo'' favoured similar environments. The sediment records at the majority of fossil ''Ginkgo'' localities indicate it grew primarily in disturbed environments along streams and levees. ''Ginkgo'' therefore presents an "ecological paradox" because, while it possesses some favourable traits for living in disturbed environments (clonal reproduction), many of its other life-history traits (slow growth, large seed size, late reproductive maturity) are the opposite of those exhibited by modern plants that thrive in disturbed settings. Given the slow rate of evolution of the genus, it is possible that ''Ginkgo'' represents a pre- angiosperm strategy for survival in disturbed streamside environments. ''Ginkgo'' evolved in an era before flowering plants, when

fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes exce ...

s, and cycadeoids dominated disturbed streamside environments, forming a low, open, shrubby canopy. The large seeds of ''Ginkgo'' and its habit of "bolting"—growing to a height of before elongating its side branches—may be adaptations to such an environment. Diversity in the genus ''Ginkgo'' dropped through the Cretaceous (along with that of ferns, cycads, and cycadeoids) at the same time the flowering plants were on the rise, which supports the notion that flowering plants, with their better adaptations to disturbance, displaced ''Ginkgo'' and its associates over time. '' Trichopitys heteromorpha'' from the earliest Permian of France, is one of the earliest fossils ascribed to the Ginkgophyta. It had multiple-forked non-laminar leaves with cylindrical, thread-like ultimate divisions. ''

Sphenobaiera ''Sphenobaiera'' is a form genus for plant leaves found in rocks from Triassic to Cretaceous periods. The genus ''Sphenobaiera'' is used for plants with wedge-shaped leaves that can be distinguished from ''Ginkgo'', ''Ginkgoites'' and ''Baiera'' ...

'' (early Permian-Cretaceous) had wedge-shaped leaves divided into narrow dichotomously-veined lobes, lacking distinct petioles (leaf stalks). ''Baiera'' (Triassic-Jurassic) had similar multiple-lobed leaves but with petioles.

Phylogeny

, molecular phylogenetic studies have produced at least six different placements of ''Ginkgo'' relative to

s, conifers, gnetophytes and

angiosperms Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants ...

. The two most common are that ''Ginkgo'' is a sister to a clade composed of conifers and gnetophytes and that ''Ginkgo'' and cycads form a clade within the

gymnosperm The gymnosperms ( lit. revealed seeds) are a group of seed-producing plants that includes conifers, cycads, '' Ginkgo'', and gnetophytes, forming the clade Gymnospermae. The term ''gymnosperm'' comes from the composite word in el, γυμν ...

s. A 2013 study examined the reasons for the discrepant results and concluded that the best support was for the

monophyly In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

of ''Ginkgo'' and cycads.

Etymology

The genus name is regarded as a misspelling of the Japanese pronunciation ''gin kyo'' for the

kanji are the logographic Chinese characters taken from the Chinese family of scripts, Chinese script and used in the writing of Japanese language, Japanese. They were made a major part of the Japanese writing system during the time of Old Japanese ...

銀杏 meaning "silver apricot", which is found in

Chinese herbology Chinese herbology () is the theory of traditional Chinese herbal therapy, which accounts for the majority of treatments in traditional Chinese medicine (TCM). A ''Nature'' editorial described TCM as "fraught with pseudoscience", and said that t ...

literature such as (Daily Use Materia Medica) (1329) and ''

Compendium of Materia Medica The ''Bencao gangmu'', known in English as the ''Compendium of Materia Medica'' or ''Great Pharmacopoeia'', is an encyclopedic gathering of medicine, natural history, and Chinese herbology compiled and edited by Li Shizhen and published in the ...

'' published in 1578.T. Hori, A historical survey of Ginkgo biloba based on Japanese and Chinese classical literatures, Plant Morphology, 2001, 31, 31-40 Despite its spelling, which is due to a complicated etymology including a transcription error, "ginkgo" is usually pronounced , which has given rise to the common alternative spelling "gingko". The

spelling pronunciation A spelling pronunciation is the pronunciation of a word according to its spelling when this differs from a longstanding standard or traditional pronunciation. Words that are spelled with letters that were never pronounced or that were not pronounc ...

is also documented in some dictionaries.

Engelbert Kaempfer Engelbert Kaempfer (16 September 16512 November 1716) was a German naturalist, physician, explorer and writer known for his tour of Russia, Persia, India, Southeast Asia, and Japan between 1683 and 1693. He wrote two books about his travels. ''A ...

first introduced the spelling ''ginkgo'' in his book ''Amoenitatum Exoticarum''. It is considered that he may have misspelled "Ginkyo" as "Ginkgo". This misspelling was included by

Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement in 1761 as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalise ...

in his book ''Mantissa plantarum II'' and has become the name of the tree's genus.

References

Citations

Sources

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External links

{{Authority control Extant Permian first appearances Gymnosperm genera Permian plants Prehistoric gymnosperm genera Taxa named by Carl Linnaeus