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March 8, 2014 |
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Taxobox_image | image =Image:Gingko_leaf.jpg|240px | caption = Ginkgo leaf Taxobox_begin_placement | color = lightgreen Taxobox_regnum_entry | taxon = Plantae Taxobox_divisio_entry | taxon = Ginkgophyta Taxobox_classis_entry | taxon = Ginkgoopsida Taxobox_ordo_entry | taxon = Ginkgoales Taxobox_familia_entry | taxon = Ginkgoaceae Taxobox_genus_entry | taxon = Ginkgo Taxobox_species_entry | taxon = G. biloba Taxobox_end_placement Taxobox_section_binomial_botany | color = lightgreen| binomial_name = Ginkgo biloba| author = Carolus Linnaeus|L. Taxobox_end The Ginkgo (Ginkgo biloba), sometimes also known as the Maidenhair tree, is a unique tree with no living relatives. It is classified in its own division, the Ginkgophyta, comprising the single class Ginkgoopsida, order Ginkgoales, family Ginkgoaceae, genus Ginkgo and just the one species. It is one of the best examples of a living fossil known. In the past it has also been placed in the divisions Spermatophyta or Pinophyta. Ginkgo is a gymnosperm (as opposed to an angiosperm), meaning "naked seed"; its seed embryos are not protected by a seed shell at pollination, but are exposed to the air. The Ginkgo is a medium-large deciduous tree, reaching 20-35 m tall, with an often angular crown with long, somewhat erratic branches. They are very long-lived, with some specimens thought to be more than 2,500 years old. Image:Ginkgo biloba0.jpg|left|thumb|Ginkgo fruit and leaves The leaf|leaves are unique among seed-bearing plants, being fan-shaped with veins radiating out with the leaf blade, sometimes bifurcating but never anastomosing (branching); they are 5-15 cm long. The old popular name "Maidenhair tree" is because the leaves resemble some of the pinnae of the Maidenhair fern Adiantum capillus-veneris. Sometimes leaves are notched or lobed, but only from the outer surface, between the veins. The leaves are borne both on the more rapidly-growing branch tips, where they are alternate and spaced out, and also on short, stubby spur shoots, where they are clustered at the tips. The seed is 1.5-2 cm long and contained inside a light yellow-brown coloured, soft fruit-like coating 2-3 cm in diameter. It is plum-like and attractive, but contains butanoic acid and thus smells like rancid butter (which contains the same chemical). Some people are sensitive to this or other chemicals in the ovary pulp, and when cleaning the seeds they should be handled with care, wearing disposable gloves, if sensitive. The symptoms are a rash or Blister|blisters similar to that from Poison ivy|poison-ivy. The seed is edible after shelling and after being cooked. Japanese cooks add it to dishes such as chawammushi. The seed are a traditional Chinese food, often served at weddings, and sometimes believed to have health benefits; some also consider them to have aphrodisiac qualities (unproven!). The trees are easy to propagate from seed. Image:Gingko biloba3.jpg|left|thumb|Ginkgo ripe fruit and autumn leaf colour The sexes are separate, some trees being female and others being male. In some areas, most trees planted are male stock grafted onto roots propagated from seed, because the male trees will not produce the fleshy, smelly, ovaries. The name Ginkgo means "silver apricot" (銀杏 y?n x?ng) in Chinese language|Chinese. The same name was used in Japan (where Ginkgo had been introduced from China) in the 17th century, but the Japanese pronunciation was ginkyō. This was the name encountered by Engelbert Kaempfer, the first Westerner to see the species, in 1690. The modern Japanese reading is ichō or ginnan (although the kanji text is the same). The modern Chinese name is 白果 (bái guǒ), meaning "white fruit". Image:Fossil Plant Ginkgo.jpg|right|thumb|Fossil Ginkgo leaves from the Jurassic of England The Ginkgo is a living fossil, with fossils recognisably related to modern Ginkgo from the Permian, dating back 270 million years. They spread and diversified throughout Laurasia during the middle Jurassic and Cretaceous, but became much rarer thereafter. By the Paleocene, Ginkgo adiantoides was the only Ginkgo species left, and at the end of the Pliocene Ginkgo fossils disappeared from fossil record everywhere apart from a small area of central China where the modern species survived. Ginkgophyta fossils have been classified in the following families and genera:
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. It has long been cultivated in China; some planted trees at temples are believed to be over 1,500 years old. The first record of Europeans coming across it is in 1690 in Japanese temple gardens. Even so, for centuries it was thought to be extinct in the wild, but is now known to grow in at least two small areas in western China. Because of its status in Buddhism and Confucianism, the Ginkgo is also widely planted in Korea and parts of Japan; in both areas, some naturalisation has occurred, with Ginkgos seeding into natural forests. Image:Ginkgo-penjing-montreal-botanical-gardens.jpg|thumb|right|Ginkgo as penjing in the Montreal Botanical Gardens Ginkgos are popular subjects for growing as penjing and bonsai; they can be kept artificially small and tended over centuries. The Ginkgo has the intriguing distinction of being one of the world's most urban-tolerant trees, often growing where other trees cannot survive. Some claim that only one tree, the Ailanthus|Tree-of-heaven, is more urban-tolerant. This makes it all the more puzzling why all of its relatives died out. For this reason, and for their general beauty, they are excellent urban trees. Extreme examples of the Ginkgo's tenacity may be seen in Hiroshima, Japan, where four trees growing between 1-2 km from the 1945 atom bomb explosion were the only living things in the area to survive the blast (http://www.xs4all.nl/~kwanten/hiroshima.htm photos & details). Extracts from the Ginkgo leaves contain flavonoid glycosides, among others, ginkgolides and are therefore used as a pharmaceutical. The extract has many properties but it is mainly used as memory enhancer and anti-vertigo agents. However, studies differ about its efficacy. Benefits Throughout the past three decades, more than 300 studies have shown Ginkgo biloba to provide a number of benefits. The most important are listed below.
Side effects Like all things, Ginkgo may have some undesirable effects, especially for individuals with blood circulation disorders and those taking anti-coagulants such as aspirin. It should also not be used by people who are taking the anti-depressant drugs known as monoamine oxidase inhibitors (MAOI) or pregnant women. Below are some Ginkgo side effects and cautions:
If any side effects are experienced the dosage should be lowered immediately. Ginkgo supplements are usually taken in the range of 40 mg to 200 mg per day. If the side effects continue usage should be stopped completely. The fruits of ginkgo are often used in Cantonese cooking, e.g. congee. Usually only a few are added for a portion enough for ten people. An overdose of the fruit would cause poisoning because the fruit produces hydrogen cyanide as a side product. It is known that a dozen raw ginkgo fruits are toxic enough to kill a small child.
commons|Category:Ginkgo Category:Gymnosperms da:Tempeltr? (Ginkgo biloba) de:Ginkgo es:Ginkgo sv:Ginkgo eo:Ginko fr:Ginkgo biloba he:גינקגו דו אונתי it:Ginkgo biloba nl:Ginkgo biloba ja:イチョウ pl:Miłorząb dwuklapowy pt:Ginkgo zh:银杏 This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Ginkgo".
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