An ode to the ginkgo, as its fleeting golden leaves arrive in the last show of summer
Excerpts from BETH BOTTS, MORTON ARBORETUM. CHICAGO TRIBUNE | SEP 27, 2020
Every fall, there comes a moment as lovely and fleeting as a visit from a butterfly: when the ginkgo trees are golden. The incandescent yellow lasts for just a few days — sometimes only one — and then the leaves seem to all rain to ground at once, like the last shower of summer.
Ginkgo trees (Ginkgo biloba) are common along city streets throughout North America and Europe. “It’s a very widely planted ornamental tree,” said Kris Bachtell, vice president of collections and facilities at The Morton Arboretum in Lisle. “It’s long-lived, resilient and can handle urban conditions.”
The trees prefer well-drained soil, but tolerate a wide range of soil types and resist damage from cold, wind, pests and disease. They grow up to 80 feet tall at maturity with a shape that resembles a broad pyramid.
The leaves that cloak a ginkgo’s graceful branches in summer are unique. Shaped like a fluttering fan, each has a spray of delicate veins so fine that the ginkgo is sometimes called the maidenhair tree. In spring, the emerging leaves are a vivid lime green; in fall, they turn that bright, brief gold.
The ginkgo tree is dioecious, meaning there are separate male and female trees. Most homeowners prefer to plant a male, because mature female trees can be a malodorous mess. In autumn, they drop many fruits (actually seeds with a fleshy covering) that are catnip for squirrels, but stinky to people.
“You can avoid the mess by planting a tree from a male cultivar that doesn’t produce seeds,” said Sharon Yiesla, plant knowledge specialist at the Morton Arboretum.
Among the available cultivars are Jade Butterfly ginkgo, a dwarf variety that grows just 12 to 15 feet high; Princeton Sentry ginkgo, a narrow, nearly columnar tree that tapers to a point; and Autumn Gold ginkgo, which has excellent fall color.
Fossils tell us that relatives of today’s ginkgo were among the earliest trees, growing over much of the Northern Hemisphere for 200 million years. But by the end of the ice ages, just a single species remained on mountainsides in China.
Some trees have lived for thousands of years in gardens and temple courtyards. As Japan and China opened to Western trade in the 18th century, travelers and traders took ginkgo seeds and cuttings to Europe and the United States.
Ginkgo leaves turn golden yellow in autumn. Although the ginkgo thrives as a street and ornamental tree around the world, the species is endangered in the wild in its native China
In modern times, although the species thrives widely in cities and suburbs, the ginkgo is rare and endangered in the wild and needs conservation and protection. Wild populations of trees have the most genetic diversity and conservation value, said Murphy Westwood, the Morton Arboretum’s director of global tree conservation, but ginkgos grow wild in just one province of China. Elsewhere, the tree is grown only as an ornamental tree or farmed for its purported medicinal properties.
If you are lucky enough to have a ginkgo in your yard or in the parkway in front of your house, protect it the way we need to protect all our treasured trees. “Water the tree any time it hasn’t rained for awhile and the soil is dry,” Yiesla said. “Keep lawn mowers and string trimmers away from it so they don’t damage the bark.” You can create a buffer zone by spreading mulch around the tree in a wide, even layer. Mulch also has many other benefits for the tree, insulating the soil and roots against extremes of heat and cold, holding in moisture, and gradually decaying to improve the soil.
After all, in nature, every tree’s roots live under a nourishing layer of last year’s leaves. When those golden ginkgo leaves fall to the ground, they are giving back their richness to the tree.