An ode to the ginkgo
Every fall, there comes a moment as lovely and fleeting as a visit froma butterfly: when the ginkgo trees are golden.
The incandescent yellowlasts 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 in Chicago and throughoutNorth America and Europe.
“It’s a very widely planted ornamental tree,” said Kris Bachtell, vice president of collections and facilities at TheMorton Arboretum in Lisle. “It’s long-lived, resilient and can handle urban conditions.”
The trees preferwelldrained soil, but tolerate a wide range of soil types and resist damage from cold, wind, pests and disease. They growup 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 male and female trees. Most homeowners prefer to plant amale, because mature female trees can be amalodorousmess. 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 froma male cultivar that doesn’t produce seeds,” said Sharon Yiesla, plant knowledge specialist at the Arboretum’s Plant Clinic.
Among the available cultivars are Jade Butterfly ginkgo, a dwarf variety that grows 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. Find more cultivars through the Tree and Plant Finder at mortonarb.org/ plantadvice, or consult the Plant Clinic.
The ginkgo treewas a favorite of JoyMorton, the founder of the Arboretum, which had its first ginkgo planted in 1926. Yet this tree’s history is much more ancient. Fossils tell us that relatives of today’s ginkgo were among the earliest trees, growing over much of theNorthernHemisphere for 200 million years. But by the end of the ice ages, just a single species remained on mountainsides in China.
Still, these trees survived. As civilization spread in Asia, people embraced the beauty and strength of the ginkgo.
Some trees have lived for thousands of years in gardens and temple courtyards. As Japan and China opened toWestern trade in the 18th century, travelers and traders took ginkgo seeds and cuttings to Europe and theUnited States.
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, saidMurphyWestwood, the Arboretum’s director of global tree conservation, but ginkgos growwild 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, protect it the waywe 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, they are giving back their richness to the tree.