Saturday, December 31, 2011

Ginkgo biloba


Description
Scientific Names: Ginkgo biloba
Common Names: Maidenhair Tree, Ginkgo
Plant Type: Large-size deciduous conifer tree.
Height: Grow an average 20–35 m (66–115 feet), with some specimens in China being over 50 m (164 feet).
Native Habitat: Many specimens are found along stream banks, rocky slopes, and cliff edges.
Native Range: Ginkgo biloba and other species of the same genus had spread throughout the world is expressed, but their numbers declined rapidly in two million years ago. For centuries, considered extinct in the wild, but now known to remain in two small province of Zhejiang in East China and in the Tian Mu Shan Reserve.
Conservation Status: After the declared extinct and then rediscovered, now this species has been widespread in cultivation.
Cultivation: Easily grown in average, medium moisture soil in full sun. Prefers moist, sandy, well drained soils. Tolerant of a wide range of soil conditions including both alkaline and acidic soils and compacted soils. Also tolerant of saline conditions, air pollution and heat. Fits well to most urban areas.
Bloom Time: April.


Ginkgo biloba are large trees, normally reaching a height of 20–35 m (66–115 feet), with some specimens in China being over 50 m (164 feet). The tree has an angular crown and long, somewhat erratic branches, and is usually deep rooted and resistant to damage from wind and snow. Young trees are often tall and slender, and sparsely branched, the crown becomes broader as the tree aged. A combination of disease resistance, insect-resistant wood and the ability to form aerial roots and sprouts makes Ginkgo durable, with some specimens claimed that more than 2,500 years old.


Ginkgo biloba is a deciduous conifer, the unique, two-lobed, somewhat leathery, fan-shaped leaves with diverging (almost parallel) veins features. Ginkgo is the only surviving member of a group of old trees probably inhabited the earth up to 150 million years old. Ginkgo is dioecious (separate male and female trees). Female trees are very undesirable because they produce seeds encased fleshy, fruit-like coverings that are at the end of the term in the fall, messy and emit a noxious, foul odor after falling to the ground and open columns. As a result, nurseries today generally sell only male cultivars. 'Autumn Gold' is a purely male variety usually always at the end of the term to 40-50 meters with a symmetrical, broadly spreading habit. In autumn, the leaves turn bright yellow fall, then, sometimes within a very short time (1-15 days). Ginkgo is also commonly called Maidenhair Tree, which refers to the resemblance of the fan-shaped leaves to maidenhair fern leaflets (pinnae).


Reproduction method is quite unique, Ginkgo disseminates neither spores (like the ferns), nor seeds (like the graminaceous ones) but something intermediary: the ovule. The ovule is the entirety of the female germ cells i.e. the oosphere (haploid) and additional (nucellus). They have large ovules, are filled with reserve, that Ginkgo drops on the ground rather tardily in season. Formed with the higher pole of the ovule is constituted a mini cavity filled with liquid: the pollinic space. This room is a tiny opening, the micropyle, which produces a viscous drop to a grain of pollen trap when it is presented and the micropyle is closed then. Finally, pollen germinates and then generates real spermatozoïde the female swim against the cell and penetrate to merge with it.


Uses
The tree is widely cultivated and introduced, since an early period in human history, and has various uses as a food and traditional medicine. Good choice for a variety of uses, including lawn tree, street tree or shade tree. Also effective in city parks and near commercial buildings. Extracts of Ginkgo leaves contain flavonoid glycosides and terpenoids (ginkgolides, bilobalides) and have been used pharmaceutically. Ginkgo supplements are usually taken in the range of 40–200 mg per day. Recently, careful clinical trials have shown Ginkgo to be effective in treating dementia but not preventing the onset of Alzheimer's Disease in normal people.


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