Campbell Vaughn: Ginkgo tree is beautiful living fossil

One of the most exciting plants every fall because of its wonderful seasonal color is also one of the most interesting plants in history, literally.

 

Ginkgo biloba, or maidenhair tree, is an ancient “living fossil” that is considered one of the oldest plants on earth. Based on fossil evidence, it has been around since the dinosaurs of the Jurassic period over 200 million years ago. For centuries, gingko has been cultivated in China, Japan and Korea, where trees exceed 100 feet in height and live up to 1,000 years and beyond. And this tree amazingly has no known living relatives.

Not really considered a native to North America, fossils of the tree have been found in the United States. Petrified wood of ginkgo was discovered in 1927 by highway workers in Washington state and then was excavated by geologists. This petrified wood find is estimated to be over 15 million years old. In 1938, the 7,500-acre Ginkgo Petrified Forest State Park was established at the site near Vantage, Wash.

Ginkgo is dioecious, which means that there are both male trees and female trees. This can be a problem in the landscape because the females have “fruit” that smells putrid. There are plenty female ginkgos planted near sidewalks where you will have people looking for the closest dumpster for the source of the foul smell. When planting one for yourself, locate a male tree. You won’t regret it.

Ginkgo leaves are quite unique. They are shaped like a fan with two lobes and veins that are parallel. The fall color is a stunning yellow-gold, almost like sun drops. In the Zhongnan Mountains of China, there is a 1,400-year-old tree in a Buddhist temple yard that is celebrated each year. Thousands of people come from all around to see its leaves drop, sometimes waiting in line for hours. Because the leaves drop within a short time frame, there is literally a carpet of gold under the tree, which is a spectacular sight.

The reason ginkgo trees rapidly lose their leaves is also an unusual bit of biology. Deciduous trees drop their leaves in the fall at differing rates. Most deciduous trees produce chemicals that essentially cut the link between the leaf and the tree’s nutrient system. As the veins close down, the abscission layer of cells forms at the base of the leaf stem. When the process is complete, the leaf falls from the tree and the wound rapidly heals itself. In the ginkgo, this happens in a matter of days while in most trees leaf drop happens over a period of weeks.

Ginkgo makes a great street tree and can withstand harsh environments. Relatively slow growing, they are remarkably free of any diseases and insects. In its youth, the tree has a single trunk, but with age, become more oval with a spreading canopy.

The City of Augusta has a bunch of ginkgo lining Ninth Street downtown that have made a beautiful display of yellow gold this autumn. One of the best local single specimens of a ginkgo is on the grounds of the Old Government House, which is thought to have been planted in honor of George Washington’s visit to our city. Some think it might have been planted for Thomas Jefferson. Either way, that awesome tree is well worth the visit.

 

Reach Campbell Vaughn, the UGA Agriculture and Natural Resource agent for Richmond County, by e-mailing augusta@uga.edu.

 

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