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Ginkgo
Fossil range: 199.6–0 Ma
Jurassic[1] to recent
Ginkgo biloba Eocene, MacAbee, B.C., Canada.
Scientific classification
Kingdom: Plantae
Division: Ginkgophyta
Class: Ginkgoopsida
Order: Ginkgoales
Family: Ginkgoaceae
Genus: Ginkgo
L.
Species
  • Ginkgo adiantoides
  • Ginkgo biloba
  • Ginkgo digitata
  • Ginkgo dissecta
  • Ginkgo huttonii
  • Ginkgo yimaensis
Synonyms

Salisburia Sm.[2]

Ginkgo is a genus of highly unusual non-flowering plants with one extant species, G. biloba, which is regarded as a living fossil.

Prehistory

The Ginkgo is a living fossil, with fossils recognisably related to modern Ginkgo from the Permian, dating back 270 million years. The most plausible ancestral group for the order Ginkgoales is the Pteridospermatophyta, also known as the "seed ferns," specifically the order Peltaspermales. The closest living relatives of the clade are the cycads,[3] which share with the extant G. biloba the characteristic of motile sperm. Fossils attributable to the genus Ginkgo first appeared in the Early Jurassic, and the genus diversified and spread throughout Laurasia during the middle Jurassic and Early Cretaceous. It declined in diversity as the Cretaceous progressed, and by the Paleocene, Ginkgo adiantoides was the only Ginkgo species left in the Northern Hemisphere while a markedly different (and poorly documented) form persisted in the Southern Hemisphere. At the end of the Pliocene, Ginkgo fossils disappeared from the fossil record everywhere except in a small area of central China where the modern species survived. It is doubtful whether the Northern Hemisphere fossil species of Ginkgo 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 the Cenozoic: present-day G. biloba (including G. adiantoides) and G. gardneri from the Paleocene of Scotland.[4]

Fossil Ginkgo leaves from the Jurassic of England

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 ecotypes or subspecies. The implications would be that G. biloba had occurred over an extremely wide range, had remarkable genetic flexibility and, though evolving 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).[5]

Modern-day G. biloba grows best in environments that are well-watered and drained,[6] and the extremely similar fossil Ginkgo favored similar environments: the sediment record at the majority of fossil Ginkgo localities indicates it grew primarily in disturbed environments along streams and levees.[5] 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 (slow growth, large seed size, late reproductive maturity) are the opposite of those exhibited by modern plants that thrive in disturbed settings.[7]

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 ferns, cycads, and cycadeoids dominated disturbed streamside environments, forming a low, open, shrubby canopy. Ginkgo's large seeds and habit of "bolting" - growing to a height of 10 m before elongating its side branches - may be adaptions to such an environment. The fact that diversity in the genus Ginkgo drops through the Cretaceous (along with that of ferns, cycads, and cycadeoids) at the same time that flowering plants were on the rise, supports the notion that flowering plants with better adaptations to disturbance displaced Ginkgo and its associates over time.[8]

Ginkgo has been used for classifying plants with leaves that have more than four veins per segment, while Baiera for those with less than four veins per segment. Sphenobaiera has been used to classify plants with a broadly wedge-shaped leaf that lacks a distinct leaf stem. Trichopitys is distinguished by having multiple-forked leaves with cylindrical (not flattened) thread-like ultimate divisions; it is one of the earliest fossils ascribed to the Ginkgophyta.

References

  1. ^ Taylor, Thomas N.; Edith L. Taylor (1993). The Biology and Evolution of Fossil Plants. Englewood Cliffs, NJ: Prentice Hall. pp. 138, 197. ISBN 0-13-651589-4. 
  2. ^ "Genus: Ginkgo L.". Germplasm Resources Information Network (GRIN). United States Department of Agriculture, Agricultural Research Service, Beltsville Area. http://www.ars-grin.gov/cgi-bin/npgs/html/genus.pl?4960. Retrieved 2008-03-26. 
  3. ^ Royer et al., p.84.
  4. ^ Royer et al., p.85.
  5. ^ a b Royer et al., p.91.
  6. ^ Royer et al., p.87.
  7. ^ Royer et al., p.92.
  8. ^ Royer et al., p.93.

Sources

  • Royer, Dana L.; Hickey, Leo J.; Wing, Scott L. Ecological Conservatism in the "Living Fossil" Ginkgo. Paleobiology, (29)1, 2003, 84-104.

Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

See also ginkgo

Contents

Translingual

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Etymology

From Chinese 銀杏 (yínxìng) "silver apricot". The same characters are used in Japanese (ichō) and Korean (eunhang). The Japanese characters used to write ginkgo look as though they could be read ginkyō, and this was the name Engelbert Kaempfer, the first Westerner to see the species in 1690, wrote down in his Amoenitates Exoticae (1712). However, his y was misread as a g, and the misspelling stuck.

Proper noun

Ginkgo

  1. (botany): A botanical name for a genus of gymnosperm trees with fan-shaped leaves.
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Wikispecies

Synonyms

  • maidenhair tree

See also


Wikispecies

Up to date as of January 23, 2010

From Wikispecies

Taxonavigation

Main Page
Cladus: Eukaryota
Regnum: Plantae
Division: Ginkgophyta
Classis: Ginkgoopsida
Ordo: Ginkgoales
Familia: Ginkgoaceae
Genus: Ginkgo
Species: G. biloba - †G. dissecta

Name

Ginkgo Linnaeus, 1771

Synonyms

  • Gingko
  • Gingkyo
  • Ginko
  • Ginkyo

References

Vernacular names

Česky: jinan
Deutsch: Ginkgo
English: Ginkgo
Español: Ginkgo
Français: Ginkgo
Galego: Xinkgo
한국어: 은행나무
Македонски: Гинко билоба
Wikimedia Commons For more multimedia, look at Ginkgo biloba on Wikimedia Commons.

Simple English

Ginkgo
Fossil range: Jurassic - Pliocene[1]
Conservation status
Scientific classification
Kingdom: Plantae
Division: Ginkgophyta
Class: Ginkgoopsida
Order: Ginkgoales
Family: Ginkgoaceae
Genus: Ginkgo

The ginkgo is a plant. It is a tree. The tree is special in that there are no other trees that look like it. Some people say it is a living fossil. It is grown mainly in China, but also lives there in the wild.

References








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