This tree was formally part of an extensive group of plants, but is now represented by a solitary genus: Ginkgo, or maidenhair tree. Ginkgos appeared during the early Permian Period (about 270 million years ago) and were at their height during the Jurassic Period (206 to 142 million years ago). Ginkgos, along with cycads, cycadeoids and conifers, formed the forests of the Jurassic Period. All the members had a characteristic fan-shaped leaf. The leaves of the tree are divided into two lobes, hence the species name biloba. Ginkgo biloba is in the family Ginkgoaceae.
By the start of the Oligocene Epoch, about 37 million years ago, only two out of 19 ginkgo species remained. During the Miocene Epoch, 24 million to 5.3 million years ago, the species disappeared from the fossil record in western North America. Since then our present evidence indicates that the Order Ginkgoales is represented by the sole living species, Ginkgo biloba of China.
Ginkgo biloba is known as a “living fossil” – a living species that has persisted over a very long interval of geologic time; many millions of years. Ginkgo’s natural habitat is southeastern China (Chekiang Province) but it has been introduced as an ornamental tree in many parks, gardens and streets in the U.S. The tree is dioecious, having male and female flowers on separate plants of the same species. The mature seeds have the appearance of small plums. Male trees are preferred in cultivation, because the outer layer of the fruit decays and smells like rancid butter. Ginkgo will grow well in most types of soil.
Name: Ginkgo biloba
Common name: Maidenhair tree
Hardiness: Zones 4 to 9
Mature height: 60 to 70 feet
Mature spread: About 30 to 40 feet
Classification: Deciduous tree
Landscape Use: Streets, parks, gardens, college grounds, cemeteries
Ornamental Characteristics: Fan-shaped leaves; outer margins entire or split; mustard yellow fall color
PHOTOS COURTESY OF SALLY BENSON
The name maidenhair tree alludes to the resemblance of the leaves to that of the maidenhair fern. Ginkgo’s leaves are quite distinctive, having a fan shape with parallel veins and the outer margin split, or entire. This hardy tree is resistant to smoke, dust, ozone, wind, ice, insect pests and disease.
Ginkgo is a gymnosperm, a vascular plant that produces naked seeds. The genus Ginkgo is related to conifers and cycads, in that they are all gymnosperms. Ginkgo biloba is propagated by seed, cutting, grafting and layering.
Medicinally, the most notable attribute of the tree’s extract, made from the leaves, is its antioxidant, free-radical scavenging properties. Like vitamin A, vitamin C, vitamin E and selenium, ginkgo biloba extract helps to purge the body of potentially damaging free radicals.
In recent years I discovered on Massie Road in Richmond, Va., a grove of Ginkgo biloba trees lining both sides of the Road. These are mature specimens, about 60 feet in height. Their fall foliage color is a lovely mustard yellow. Ginkgo is deciduous, and the colorful autumn leaves can all fall rapidly in a single day or over a few days. I would recommend Ginkgo biloba in the landscape for its interesting fan-shaped leaves, rich yellow fall color, and its unique status as a “living fossil.”
Retired landscape gardener