Agroforestree Database

Local names:
 Chinese (ya-chiao,ginkyo,ginnan,pakgor su,paikua su,yinxing,gong sun shu,icho,fozhijia), Dutch (Japanse notenboom,waaierboom,tempelboom,ginkgo), English (ginkgo,Kew tree,golden fossil tree,maiden-hair tree), French (arbre des pagodes,arbre de Gordon,noye

Ginkgo biloba belongs to single plant division Ginkgopsida which consists of the single order Ginkgoales, a single family Ginkgoaceae and a single extant genus Ginkgo. The tree is deciduous reaching a height of 4 m, with a reddish bark. Male specimens show an upright and irregular form, female trees are low and spreading. 

Leaves fan-shaped glossy green (resembling those of the maidenhair fern or Adiantum), with irregularly toothed upper margins. Numerously veined, with a split in the middle and therefore appears to have two lobes. The leaves turn golden yellow before they fall.

The flowers are rather inconspicuous and grow on short spurs.Trees flower after 20-35 years, females exhibiting an abundance of ovules in pairs on stalks each containing an egg cell, initially very green, but later turning greenish-yellow, then orange and brown. The male flowers are yellow catkin-like pollen cones (microsporangia), 3-6 on each short shoot in the spring. 

A single naked ovule ripens into a drupe-like seed with an acrid, ill-smelling fleshy outer layer and a thin, smooth, horny inner layer. The fleshy-coated seeds silvery are frequently incorrectly designated as fruits or nuts. 

The generic name Ginkgo comes from the Chinese (later also Japanese) word ginkyo meaning 'silver apricot'. The specific name biloba means two-lobed: bi from the Latin 'bis' meaning double and 'loba' meaning leaf, which is an obvious reference to the fan-shaped leaves which have a split in the middle.

Ecology

Ginkgo is a hardy tree tolerating a variety of climate and soil types. It does not tolerate extreme frost.

Native range
China, Japan, Taiwan, Province of China, Turkey

Tree management

Generally the tree is very adaptable, tolerating all climates and soils. The tree takes 30 years to reach a height of 10 metres. Application of pollen by spraying was found to be the best method for increasing fruits quantity and quality. For ornamental gardens it is advisable to plant male trees only, because the female trees produce malodorous fruits.

Removal of the sarcotesta significantly increases the total germination. In one study cold stratification, an unnecessary treatment, improved seed germination percentage.

Ginkgo is a hardy tree tolerating a variety of climate and soil types. It does not tolerate extreme frost.

Ginkgo is propagated by direct seeding, soft wood cuttings or grafting to avoid female specimens. Germination begins 33 days after planting in a warm place, if planted in cold soil, germination is deferred until the soil warms in the spring. The seeds may be grown in gallon pots for a year or two before transplanting seedlings to their permanent location in the garden or landscape. The results of grafting experiments of G. biloba Gui 86-1 indicate that February-March and September-November are suitable periods for grafting. The highest grafting survival rates with 2-year seedling stock and current growing scion were 98% and 93% respectively. Treatment of 2-25 cm long cuttings of G. biloba with crystalline KMnO4 results in higher rooting rates compared with treatment of the same species with growth regulator powders (IBA & IAA).

Poison:  4'-O-Methylpyridoxine (ginkgotoxin) is a neurotoxic antivitamin B6 which occurs in G. biloba seeds and leaves. However, toxin amount is likely to be too low to exert detrimental effects after administration of the medication or ingestion of food. Leaf extracts of G. biloba are shown to be highly effective against the rice pest Nilaparvata lugens resistant to diazinon, carbofuran and fenobucarb (Kwon-Min et al. 1996). Extracts of powdered dried leaves were deterrent to P. brassicae and P. rapae at levels as low as 25-50 p.p.m.

This tree is hardy, surviving polluted environments remarkably. Ginkgo is a suitable tree for urban forestry.

  Various foods and drinks are made from the fruits, seeds and leaves. The seeds may be roasted and are considered a great delicacy. Seeds are high in starch, but low in protein and oil.

Shade or shelter:  The maidenhair tree is an excellent shade tree.

Medicine:  In Traditional Chinese Medicine the seeds (used as an astringent for the lung, to stop asthma, enuresis, and excessive leucorrhea and regulate urinary frequency) are considered more important than the leaves. However, in the west ginkgo leaves are exalted. The leaves of ginkgo, known in Chinese medicine as bai-guo-ye are first mentioned in Lan Mao's Dian Nan Ben Cao (Pharmaceutical Natural History of Southern Yunnan), published in 1436 during the Ming dynasty, are used externally to treat skin and head sores as well as freckles. Internal use of the leaves is noted in an imperial commissioned work recorded in 1505 for the treatment of diarrhoea. Over 300 scientific studies on the chemistry, pharmacology and clinical effects of gingko leaf have been conducted by European researchers over the last 20-30 years. The experimental results indicate ginkgo leaf extracts have a wide range of biological effects. The most well-known use among Americans is the perceived ability of the products to improve short term memory. Ginkgo extracts have been widely used in Europe for a wide variety of clinical conditions including vertigo, tinnitus (ringing in the ear), treatment of poor circulation, heart disease, eye diseases, chronic cerebral insufficiency, accidents involving brain trauma, dementia, and various conditions associated with senility. Studies have shown that the constituents ginkgoic acid and ginnol inhibit certain bacteria and fungal infections. New uses for ginkgo leaf extracts are emerging as more is being learned, especially those involving circulatory problems such as erectile dysfunction and improved memory, blood circulation. Also marketed as Shun Tian capsules, containing gingko leaves and ginseng.

Nitrogen fixing:  G. biloba roots are colonized by the fungus Glomus epigaeum, forming vesicular arbiscular mycorrhiza.

Ornamental:  Ginkgo has been widely adopted as an ornamental tree in many European and American cities.

Soil improver:  Leaf litter of the maidenhair tree improves soil fertility.

Other services:  Ginkgo figures strongly in legend and lore of China, and has been lovingly adopted by most cultures in the temperate regions of earth.