Family: GINKGOACEAE. Interestingly the Ginkgo tree is the only living tree in this family surviving since the Mesozoic period (252-66 million years ago) the age when Conifer’s and Cycad’s dominated the earth. It is therefore classed by some as a living fossil.
Common Name: Ginkgo or Maidenhair tree.
Etymology: Ginkgo: Named by Engelbert Kaempfer (German naturalist). Ginkgo comes from a misinterpreted Japanese spelling of the trees name in 1690. biloba: From Latin ‘bis’ meaning double and ‘loba’ meaning leaf.
Origin: China, Japan, Taiwan and Turkey. The Ginkgo tree was thought to be extinct in the wild until it was found in Zhejiang province in eastern China. There is, however, still doubt whether these are completely natural and it is even believed that the species may not have survived into modern times without the preservation and planting of trees in temple grounds in China. It is classed as endangered.
Description: Large, deciduous, long lived tree (up to 2500 years so it is claimed, maybe closer to 1500 years) to 35m (can grow to 50m) and 9m spread. The Ginkgo is deciduous and is also dioecious, male trees being upright and irregular while females are lower and spreading. In saying this the younger trees tend to be tall and slender becoming broader with age (the reason for this is explained in Growth Requirements section). Trees are deep rooted and resistant to wind and snow damage. Interestingly the Ginkgo is capable of producing chemicals to repel insects, fungi and bacteria while simultaneously producing other chemicals to attract enemies of attacking enemies. The Ginkgo biloba genome has some 10.6 billion DNA letters compared to humans that have roughly 3.2 billion. It appears that this genome pool has increased over time meaning the tree is becoming increasingly better at survival.
Foliage: The leaves are 5-10cm long (sometimes up to 15cm) irregularly toothed, convex and fan-shaped resembling the maidenhair fern leaf, hence the common name. Deciduous, leaves go from glossy green to yellow before falling for the winter months, this can often happen in relatively short time period of time.
Bark/Trunk: Grey, sometimes reddish trunk with deeply fissured bark. Wood is soft (so not useful commercially) and insect resistant. It has the ability to form aerial roots that can help it combat erosion.
Flowers: Inconspicuous yellow catkin-like cones.
Fruit: A single naked ovule ripens into a fleshy (outer layer is acrid smelling), plum-like orange brown fruit in late summer and autumn provided male and female trees are present. Does not fruit until at least 20 years old.
Growth Requirements: Prefers deep, fertile, well watered and well drained soils. Full sun but is relatively shade tolerant. Ginkgo does prefer disturbed sites such as along stream banks. Its habit of growing thin and straight prior to broadening out appears to stems back to a time before flowering plants when the Ginkgo would be the first to fill the disturbed area, its ability to produce aerial roots suggest the same. Ginkgo comes from a temperate climate but is quite hardy to a number of climates although does not tolerate extreme frost.
Uses: Street tree (male trees are preferred as they do not drop smelly fruit), large gardens and parkland areas, pollution resistant, large shade tree. Other uses include; seeds are edible and nutritious being eaten in China (where the female trees are preferred over male), seeds are boiled with coconut as a dessert in Thailand and they are added to dishes in Japan. Although good in small doses if eaten in large quantities over a long period of time can cause poisoning. Ginkgo extract is sold as a supplement to improve memory and is even being studied as a possible treatment for Alzheimer’s disease (although not proven). It is the official tree of Tokyo where the symbol of the city is the Ginkgo leaf.
Propagation: From seed or cutting. Seeds can be collected in Autumn, outer layer washed away, warm stratified for 2 months allowing embryo to form then cold stratified for two months all the time ensuring seeds remain moist. Then they are ready for planting. Cuttings are popular because the sex of tree is know instantly, they can be grown easily from softwood cuttings in Spring which develop roots in a few weeks and are ready for planting.
Autumn colours coming on Kumamoto.
Sources of Information:
- Botanica’s Pocket ‘Trees & Shrubs.
- Photography by Simon Schubert.