Horticulture Highlight: Ginkgo biloba
Ginkgo biloba, the ginkgo tree, can be one of our most spectacular trees for golden, autumn color. The long-stalked, fan-shaped, simple, leaves are 2-3 inches long, and wide, and occur in clusters of 3-5, on short spurs along the tree’s branch stems. There sometimes is a notch along the broad summit of some of its leaves, creating a butterfly-shape, and hence the epithet “biloba.” In late-autumn there is a tendency for most of a tree’s leaves to curiously all fall off, during a one-to-five-day period of time, hence the Nemerov poem.
The Ginkgo has been termed a “living fossil” and an “emblem of changelessness”. It is one of the oldest surviving tree taxa on earth, with fossils of related species found that date back to at least 270-million years ago. This heritage is to a time beyond when dinosaurs thrived and roamed the earth. Today, Ginkgo biloba is termed monotypic, meaning it is the only species in the genus. Additionally Ginkgo is the only genus in the family, GINKGOACEAE.
Ginkgo biloba is native to Eastern China, and during the Han Dynasty (206 BC – AD 220) it was known as a holy tree. In China, it has been the subject of poems and paintings, from the 11th century. Introduced into Japan from the Yangtze River delta region, it was in Japan, in 1690, that the German, naturalist-explorer, Engelbert Kaempfer (1651-1716) first observed Ginkgo in a Japanese temple garden and gave the plant the name Ginkgo. The first live trees arrived in Europe at the Utrecht Botanic Garden, Netherlands, about 1730. It first came to the United States from London, in 1785, to the Philadelphia area. Today, in Philadelphia, at Bartram’s Garden, one surviving tree planted in 1785 is commonly recognized as the oldest Ginkgo in the U. S. In China there are individual trees known to be older than 1000-years, and some have speculated that Ginkgo may live as long as 2000 years.
The inconspicuous flowers of Ginkgo biloba, which occur in the spring, are deciduous, meaning there are separate male and female trees. The fruit, found only on female tree, is not a true “fruit,” but a seed with a fleshy, outer layer. This fleshy layer is orange-colored when ripe, and the source of the infamous foul odor. Inside a woody, nut-like structure contains a soft, kernel-like seed. For centuries these seeds have been considered to have medicinal value. The seeds are still marketed on a large scale and are an important Chinese export crop. Extracts from Ginkgo leaves also have several medicinal values; used to increase vasodilation and peripheral blood-flow rates, and effective in the treatment of arthritis, tinnitus, and some eye conditions.
The interesting reputation of long survivability of Ginkgo biloba is enhanced by a famous specimen still growing at the site of the 1945 atom bomb at Hiroshima, Japan. One tree located 800 yards from the epicenter had its trunk destroyed, but sprouted from its base, and it still grows there today.
We have more than two-dozen Ginkgo biloba growing at Mount Auburn! On your next autumn visit look for these living fossils on Garden Avenue, Halcyon Avenue, Magnolia Avenue, Spruce Avenue, Walnut Avenue, Pearl Avenue, Cherry Avenue, Western Avenue, Bradlee Road, Field Road, Narcissus Path, Indian Ridge Path, Robin Path, Mist Path, Arethusa Path, Sparrow Path, Aralia Path, and Ilex Path.
*This Horticulture Highlight was originally published in the November 2011 issue of the Friends of Mount Auburn electronic newsletter.