Ginkgo biloba – The Oldest Tree in the World


We planted this tree in our Main Hosta Garden, in the Fall of 2011 in memory of Diane’s mother, Gertrude.


Classification

During the time of the dinosaurs seed plants (spermatophytes) were well developed and were the most dominant vegetation on earth, especially the lush seed ferns, conifers and palmlike cycads. These primitive seed plants are called gymnosperms (meaning “naked seeds”) because their seeds are not enclosed in a ripened fruit but are protected by cones or by a fleshy seed coat.
Most gymnosperms (and flowering plants) have both sexes on the same plant, but the Ginkgo is a dioecious gymnosperm, male and female are separate trees, its seeds have a fleshy outer layer.

The Ginkgo and the cycads are the only living seed-producing plants that have motile or free swimming sperm.

In earlier classification systems the Ginkgo tree was placed in the class Coniferopsida, because it is thought to be more related to conifers than to any other gymnosperm, but the two groups appear to have evolved independently.
Although the Ginkgo is more like a conifer than a deciduous broadleaf tree it is neither, it has a unique position. Recent research suggests a much closer relationship to the cycads than to the conifers.
    
Green algae (Coccomyxa) live in symbiosis with Ginkgo tissues, recent research has shown. So far this association is not known on any other tree and  only occurs in the animal kingdom.
The Ginkgo is the sole living link between the lower and higher plants, between ferns and conifers.
 
    You can distuinguish a Ginkgo from other gymnosperms by its fan shaped and bilobed leaves. All Ginkgo trees have a relatively primitive vascular system. The veins continuously divide into two’s. This vein pattern (dichotomous venation) is unique to the Ginkgo.

Because of its unique position botanists found it difficult to classify the Ginkgo. Therefore the Ginkgo has been placed in a separate group in recent years, the division (phylum) Ginkgophyta.
This division consists of the single order Ginkgoales (Engler 1898), a single family Ginkgoaceae (Engler 1897), a single extant genus Ginkgo.

There are two extinct genera: Ginkgoites and Baiera (known from fossilized leaves).
The only living representative of the order Ginkgoales is the Ginkgo biloba.

A Ginkgo tree can reach about 30 sometimes 40 metres (100 feet) height and a spread of 9 metres. The trunk can become about 4 metres (13 feet) wide in diameter (in open areas much larger; near temples 50 m with girth 10 m grow!) and is straight columnar and sparingly branched. Some trees are very wide spreading, others are narrow.

Young trees have a central trunk, pyramidal in shape, with regular, lateral, ascending, asymmetrical branching and open growth. Older trees have an oval to upright spreading growth and sometimes irregular branching and tremendous sized limbs and trunk. When about 100 years old its canopy begins to widen.

The male tree usually has a slim column form and is slightly longer, the female tree has a wider crown and a more spread out form.
 
The Ginkgo has long and short branches growing at nearly right angles. A short branch may become a long branch and the tip of a long branch may change into a short branch. That’s why older trees may have a more irregular form. The buds are mounded with distinct form and leaf scars. The leaves grow alternate on the long branches during spring. On the ends of short, lateral shoots they grow very slowly in clusters and produce a long shoot with scattered leaves after a number of years. The short shoots also produce the seeds and pollen. The stems are tan, light brown or gray, relatively smooth and are somewhat reflective in the winter sun. Some trees tend to have branches crossing the trunk.

The girth of the trunk of the older trees may become large because of secondary growth. The tree usually loses its central leader and gives rise to several vertical trunks (“basal chichi”) that keep reaching great heights. These socalled lignotubers can also be observed on the Sumter plantation (see Usage-page) where the trees are regularly cut down to groundlevel and produce lignotubers that give new shoots and roots.

 The Ginkgo also produces peg-like structures (chi-chi = nipples, sort of “aerial” lignotubers) along the trunk and branches that can grow into the ground and form roots as well as leafy branches above because of the embedded vegetative buds, which is characteristic only for the Ginkgo. chichi with leaves (photo Sando Tomoki)The chichi (Chinese: zhong ru) seem to be connected to traumatic events, environmental stress and individual properties of a tree. It is seen with old, but also with younger trees. It is thought the chichi, its resistance against diseases, its adaptability and individual properties of the tree etc. contribute to the long history of the survival of the Ginkgo.

Inside the trunk the wood is yellow.

The bark is light brown to brownish-gray; more brown, deeply furrowed and ridged on older trees and has a corky texture.

As said before although the Ginkgo is more like a conifer than a deciduous broadleaf tree it is neither, it has a unique position. This also becomes clear when looking at the microscopic structure of the wood. It lacks vessels in the xylem but has slightly rounded tracheids giving rise to intercellular spaces (conifers have regularly close-fitting rectangular tracheids). It has beautiful crystals (called druses) consisting of calcium oxalate.
 
The leaves are an easy recognizable feature of the deciduous Ginkgo biloba. They are 5- 8 cm wide and are sometimes twice as broad although they vary in size and shape. The leathery leaves have a wax layer on both sides and are slightly thicker than other Northern tree leaves. They consist of a leaf stalk and a fan-shaped dichotomously veined blade: two parallel veins enter each blade from the point of attachment of the long leafstalk and divide repeatedly into two’s (picture click here) , are not often cross-connected (seldom fuse). The veins are slightly raised giving a ribbed appearance. The pores are recessed and limited thereby reducing waterloss from evaporation. The form is bilobed, it has no midrib and is fan-shaped. The leafstalk is also about 8 cm (3 inches) long causing the foliage to flutter in the slightest breeze.  

    The leaf resembles the leafshape of a Maidenhair fern (Adiantum), hence the plant’s nickname, the Maidenhair tree.
A deep vertical slit in the top center divides the leaf into two lobes mostly on the upper part of long branches. The leaf can also have more than two lobes, esp. on the lower part of the tree. There is great variation in the degree of lobing on the same tree and this also seems to vary from tree to tree.
The colour is gray-green to yellow- to darkgreen in summer, turning in yellow and in good years a beautiful golden yellow colour in fall. Certain selected cultivars yearly have this golden yellow colour in fall.
The leaves remain on the tree until late in the season and then can all fall rapidly in a single or a few days and even in 1 or 2 hours!

Climate zones 3 to 9 (-30/40 to +20/40 C). So from Iceland to Australia, read my Where-page.

Nearly every arboretum or botanical garden will contain specimens. The supreme specimens are to be found on temple grounds in China, Korea and Japan. In China they also grow in forests and valleys on acidic, well-drained sandy loam (pH 5-5.5) and they are cultivated below 2,000 m (see Where-page).

Jinfo Mountain
Jinfo MountainGinkgo has survived in some areas of China where the impact of glaciation was minimal. Populations of Ginkgo biloba are found across the country, but are generally associated with human activities.
Questions about the extent of Ginkgo biloba’s native range in China have been the subject of debate among botanists for well over a hundred years.
DNA analyses (Literature-page) have demonstrated that isolated Ginkgo populations in southwestern China, especially around the southern slopes of Jinfo Mountain (Jinfo Shan) of Nanchuan County at the boundary of Chongqing Municipality and Guizhou Province (28°53′N; 107°27′E) possess a significantly higher degree of genetic diversity than populations in other parts of the country. Southwestern China was less affected by cold air from Siberia during the glaciations.
The area has a mesic, warm-temperate climate with a mean annual temperature of 16.6°C and a mean annual precipitation of 1185mm, with Ginkgo trees growing mainly between elevations of 800 and 1300 m. The largest Ginkgo tree was estimated to be 2500 years old with a mean diameter of 3.69 m at breast height.
 
Tianmu Shan Reserve
click on photo to enlarge
click photo to enlarge and to view more photos
photo © Peter Del Tredici
    
Ecological work in this area, as well as in adjacent parts of Guizhou Province, has identified numerous small populations, for instance in Wuchuan County and Tuole, that can be considered to be either wild or remnants of wild plants, despite their proximity to small villages practising subsistence agriculture. Both the Jinfo Mountain and Wuchuan County populations are situated to the east of Mt Dalou. This region has the greatest biodiversity in China due to the relatively stable environment and diverse topography.
The Ginkgos on West Tianmu Mountain, which were previously considered to be wild by many researchers, may, instead, have been introduced by Buddhist monks. However, more research is needed.

The Ginkgo can have a long life span, 1,000 or older. In China the oldest Ginkgo is about 3,500 years old!

The majority of ginkgos live as a hardy ornamental tree and, being nearly cosmopolitan, specimens are planted around the globe in almost any temperate and subtropical areas. In the USA only 0.2-2% of the total number of roadside trees is a Ginkgo, in Europe this is even less (1992). The tree is farmed extensively (esp. for its medicinal use as a herb) in Europe, Japan, Korea and the USA.

In China Ginkgo trees of more than 100 years old are listed as second class protected plants of the state. Roads and buildings should give way in order to protect them well.Ginkgo tree (photo Cor Kwant)

Some people think there’s a good opportunity to plant a Ginkgo tree on special occasions like the death of a beloved one, the birth of a child, an anniversary, moving house etc.
 
The Ginkgo is listed in the IUCN Red List of Endangered Plants. Although it is cultivated and planted by humans, it is endangered, and at risk for loss of biodiversity because of propagation by cuttings rather than by seed, due to human preference for male trees.

Planting: It prefers full sun to partial sun and moist, deep, well-drained soils (preferably sandy loam), but is very adaptable, so it also grows in poor soils, compacted soils, various soil pHs, heat, drought, salt spray in winter and air pollution. Fertilize 1-2 times a year. Don’t mulch with shredded bark round the trunk, keep it airy. It roots deeply (photos of root system). The roots of most Ginkgos are infected by vesicular-arbuscular mycorrhizae (VAM) that play an important role in the uptake of the element phosphorus.
 
The Ginkgo tree is particularly resistant to insect pests and to fungal, viral and bacterial diseases as well as to ozone and sulfer dioxide pollution, fire and even radioactive radiation (atom bomb WWII). Therefore it is used as a street tree, esp. in cities, it never needs spraying.
It can tolerate snow-and icestorms. Research showes that the Ginkgo has no trouble adapting  to greenhouse-effect conditions (elevated CO2).
It is also planted as a park and landscape tree and in gardens.
It is also grown for its shade (little shade when it’s young). It is particularly easy to establish in the garden.
It initially grows somewhat slowly: it takes 10 to 12 years to become 6 metres (20 feet) tall and it takes about 20 years before it has a rounded shape.
It can be trained as an espalier (photos), hedge or climber.     .

    Plant in spring or fall. Young trees tend to grow crooked and should at first be staked. Give plenty of water (more during dry/hot periods) until they are about 6 meters (20 feet).
It is slow to recover from transplanting.

In favorable conditions the Ginkgo grows from about late May to the end of August over 30 cm per year for the first 30 years of its life. In some years it doesn’t grow at all, in others 1 meter of growth can occur, independent of watering or nutrients.
It can grow steadily in the shady understory of a forest until there is a light gap, then it can quickly grow tall and become a dominant tree.

The tree needs no pruning.
If you like, pruning on young trees can be done in early spring, older trees are seldom pruned.

Gender: the tree is dioecious, male and female trees are separate.  The sex chromosomes (XX females and  XY males, just like humans) are difficult to distinguish, so the tree’s gender is not easily classified.
The pollen and ovules grow on the short spurts, very seldom on the leaves (Ohatsuki). Occasionally both genders are found on the same tree.

After a hot summer or grown in a warm sunny position the tree produces  them more reliably.
The female tree has an abundance of ovules in pairs on stalks each containing an egg cell, looking very green on the start but turning into greenish-yellow followed by orange and brown.

 They look like cherries. It takes about 20-35 years before they appear for the first time in spring. Catkin-like pollen cones (microsporangia) containing the sperms on the male tree also grow on short shoots in spring (also after about 20-35 years) and the pollination usually takes place via the wind. The female tree can carry seeds without pollination (sterile). Variations in the cycle of pollination, fertilization and seed abscission in Ginkgo are mainly due to the latitude and the local climate of the region in which the tree is growing.
When the ovules are fertilized they develop into yellowish, plumlike seeds about 2,5 cm (1 inch) long, consisting of a large “nut” (the size of an almond) with a fleshy outer layer. The actual fertilization of the seed by free swimming sperm occurs mostly on the tree (read more here).     
Ginkgo seeds (photo Cor Kwant)
The seed has a silvery shine (“silver apricot/nut”). The ripened fleshy seedcoat when falling on the ground and decaying has a ‘disagreeable’ odour (like rancid butter) as a result of the presence of butyric (butanoic) acid, a common byproduct of many plants and animals (the same compound that in small quantities is used in perfumes) and can be very messy, making the female trees unfortunately less popular for planting in pedestrian areas. This period doesn’t last long however and much ‘trouble’ can be prevented by cleaning up the fallen seeds regularly etc. In countries like Korea, Japan and China female trees are preferred because the people appreciate the nuts! More information about the ‘smell’ of the seeds: click here.

The propagation can also be done by cuttings (the best way to ensure the gender) or by grafting a female branch onto a male plant or visa versa.

The fresh nutritious seeds (also canned with fleshy outer coat removed) are sold in markets esp. in the Orient.

The “nut” has for long been used in Chinese medicine for asthma, coughs with thick phlegm, bronchitis, digestive aid and urinary incontinence etc.

The Ginkgo is listed in the IUCN Red List of Endangered Plants.

The Ginkgo tree can grow large, therefore it is not the tree for every backyard. Selections are made to make it suitable for places with less space and also to meet with desired shapes etc. Upright, dwarf, narrow and conical, pendulous and variegated cultivars exist, search for them on the internet, ask for them at garden centers and nurseries. Cultivars  are mentioned below (but no doubt there will be many more).

Ginkgo biloba:

‘Anny’s Dwarf’: dwarf form

‘Autumn Gold’: better fall colour and/or modified broad spreading growth habit, compact form, male.view photo

‘Barabits Nana’: small bushy form, up to 2 metres.view photo

‘Beijing Gold’: shrub form, 4 m, yellow leaves also in spring and summer ( in summer somewhat striped)dotview photo

‘Bergen op Zoom’: small straight up to 4 metres.

‘Chase Manhattan’: small, tiny darkgreen leaves, compact, ideal for bonsai and rockgarden, 1.5 mdot

‘Chichi (Icho)’: smaller leaves and a textured trunk, bark has breast-shaped protuberancesdot

‘Chris’s Dwarf’ (or ‘Munchkin’?): see ‘Munchkin’

‘Chotek’: weeping form of  ‘Witches Broom’; cultivar from Czech Republic; found by Mr Horak, Bystrice pod Hostinemin. Named to tribute the house of Choteks, the family of archbishop F. M. Chotek.

‘Eastern Star’: female, bears abundant crops of large nuts.

‘Elmwood’: vertical columnar formview photo

‘Epiphylla’: female. Max. 4 m h., more wide. Seeds form on rather young plant.

‘Elsie’: upright growing, female.

‘Fairmount’: slender form, big leaves, dense pyramidal crown, male, 15 m.view photo

‘Fastigiata’: architectural vertical accent, nearly columnar form, slightly wider at the base, big leaves, male (also available as female).dotview photo

‘Geisha’: female, long pendulous branches and dark green foliage which turns lemon-yellow in  fall, heavy crops of large nuts.

‘Globosa’: Graft on stock, bulb-shaped, compact view photo

‘Globus’: Bullet-form, big leaves.

‘Golden globe’: Full head and spectacular yellow fall color. Trees are unusually densely branched for Ginkgos. Young trees have full crowns that mature in a broad, rounded head. Male. (from a seedling of Cleveland Tree Co. )view photo

‘Gresham’: Wide spreading horizontal branch habit. (from Gresham High School Ginkgos at Gresham, Oregon)view photo

‘Hayanari’: female.

‘Heksenbezem Leiden’ (Witches broom): quite compact, rounded, dwarf form, branching closely grouped,
up to 3 metres.view photo
‘Horizontalis’: tall and wide form, many side-branches.
Wide crown.view photo

‘Jade Butterfly’: dense darkgreen foliage clumps, shrubby outline, vase shaped, semi dwarf, about 3 m.view photo

‘King of Dongting’: slow growing, very big leaves.

‘Laciniata’: large deeply divided leavesdotview photo

‘Lakeview’: compact, conical to broadly pyramidal, male.view photo

‘Liberty Splendor’: broad pyramidal form with strong trunk, female.

‘Long March’: Upright growing, female is cultivated for heavy crops of tasty nuts.

‘Magyar’: uniform symmetrical branching, upright narrow pyramid form, up to 19 metres, male.

‘Mariken’:  more compact than ‘W.B.’, tall about 3 ft, w.6-10 ft, branches more or less pendulous, graft on about 5 ft stock (P. Vergeldt; from a tree in Nijmegen).dotview photo

‘Mayfield’: Narrower form than Fastigiata, tight upright, short branches, 9-12 m.view photo

‘Munchkin’ (or ‘Chris’s Dwarf’ ?): Upright habit and numerous slender branches,  it has a tendency to be more regular in shape.
Most leaves do not exceed the size of a quarter and are very dense on the plant. May eventually reach 6 ft but growth rate is around 4” a year. dot

‘Ohasuki’: up to 4 metres, halfround big leaves, female.

‘Pendula’: branches more or less pendulous (“weeping”), slow growing, decorative.dotview photoview photo+ video

‘Prague or Pragense’: low spreading and parasol-shaped.

‘Princeton Sentry’: well known cultivar, slow growing, big decorative leaves, upright conical form gives very formal focal point, male, 30 m.
Improved “Fastigiata”. Name derived from tree in Princeton Cemetary.view photo

‘Rainbow’: striped with green/yellow leaves, about 3 m. Improved ‘Variegata’. Remove green leaved branch immediately.

‘Salem Lady’: female from Oregon.

‘Santa Cruz’: female, low, spreading, umbrella-shaped.

‘Saratoga’: dense branches, small yellow-green leaves, slow growth, rounded outline, male, 10 m.view photo

‘Shangri-La’: fast growing with compact pyramidal form, 14 metres, grows somewhat faster, male.

‘Spring Grove’: dwarf, very small and compact, about 3 m.

‘Tit’: = Chichi (Icho).

‘Tremonia’: small, pyramidal form, very big leaves, female, 10 m.view photo

‘Troll’:   compact ‘W.B.’,  leaves vary from normal to rounded (Johann Wieting; from a tree in Krefeld, Germany.dotview photo

‘Tubifolia’: slender leaves form sort of tub shape, slow growing, decorative, small tree, fairly compact branching, about 3 m.view photo

‘Umbrella’: compact, densely branched, different leaf-forms and sizes.view photo

‘Variegata’:Ginkgo biloba ‘Variegata’ (photo Cor Kwant)shrub form with variegated foliage,  some leaves ‘halved’ green and gold, others striped and others half gold/half striped, up to 3 metres, female.
It often reverts to green (see ‘Rainbow’). Half-shaded position.dotview photo

‘Windover’: broad oval outline, shade tree, 17 m.