Thursday, June 15, 2017
The Ginkgo Tree - Ginkgo Biloba
The Ginkgo Tree - Ginkgo Biloba - is the survivor of all arboreal survivors. There were Ginkgo trees when dinosaurs walked the Earth. The sole remnant of a group of plants even more primitive than Conifers. It is a living fossil, and fossils relating to the modern Ginkgos dating back 270 million years. They were wiped out completely in North America by the Glaciers,and thought to at one time be extinct in the wild the world over. They however thrived in China where the Buddhist monks tended to them in their gardens. When growing in the wild , they are found infrequently in deciduous forests and valleys with fine silty soil. It has long been cultivated in China and is now common in the southern third of that country. They were exported to England in 1754 and to the U.S. about 30 years later, cultivated in both countries for over 200 years it has failed to become significantly naturalized in either.
Ginkgos are also known as Maiden Hair trees, and sometimes referred to by a variation in spelling on the name -Gingko/Gingo/Ginko. They grow to be very tall, they average between 60-100ft, with some specimens in China reaching over 160 ft tall. The tree has an angular crown and long, somewhat erratic branches. This tree is deep rooted which makes it tolerant to wind and snow damage. They grow best in moist soil, but are known to be very tolerant. Young specimens are often tall, slender, and sparcely branched, but with age the crown broadens. In the fall the leaves will turn a bright yellow before they fall often within as short a span as 15 days. Their combination of disease resistance, insect resistant wood, and their ability to form aerial roots/sprouts make them very longed lived. Some specimens in China are claimed to be over 2500 years old.
Being Dioecious, Ginkgos are either male or female. Males produce small pollen cones. Females do not produce cones, instead two ovules are formed at the end of a stalk and after pollenation one or both develop into seeds. The seed is 1-2 cm long, the outer layer is a yellowy brown flesh that is soft and fruit-like. It is attractive in appearance but contains butanoic acid (or butyric acid). The males are generally preferred in urban landscapes because the fruits from the females tend to be messy when they fall onto sidewalks and have a peculiar odor from the butanoic acid (often compared to a strong cheese). The kernel/seed (or Silver Nut) inside the fruit is considered a delicacy in the Orient. The fertilization of a Ginkgo occurs via motile sperm (as in Cycads, ferns, or moss), the sperm have a very complex structure. They adapt well in urban enviroments, tolerating pollution as well as confined soil space, for this reason as well as just being a beautiful tree they are often planted in streetside setting.
Used in both culinary and medicinal settings, the Ginkgo is thought by some to have health benefits and is also considered by others to be an aphrodisiac. However when eaten in large quantities for a number of years (especially by children) the meat of the seed can cause poisoning. Others are sensitive to the chemical in the outer fleshy part of the fruit, having symptoms similar to poison ivy. The extract of Ginkgo leaves contains flavonoid glycosides and terpenoids and have been used pharmaceutically. Medical trials have shown Ginkgo to be moderately effective in improving symptons in dementia patients, but not in preventing the onset of Alzhemiers disease in the average person. Used primarily as a memory and concentration enhancer, and anti-vertigo agent, even though some studies differ in results about its effectiveness. Ginkgos are truely an amazing species of tree all on their own, surviving and adapting for hundred of millions of years.
Image Citations (Photos 1 & 2) : Jan Samanek, State Phytosanitary Administration, Bugwood.org