Plant Profile: Ginkgo biloba (Maidenhair tree)

With unique fishtail-shaped leaves that open vibrant green in spring, becoming golden yellow in autumn, the ginkgo in full foliage is an unmistakable sight.

More closely related to conifers than to other flowering plants, it is a ‘fossil’ species—the only surviving member of a group dating back more than 200 million years.

Trees are either female or male (dioecious), and mature female trees produce tomatillo-sized fruits in summer.

Ginkgo is widely planted as a street tree, particularly in East Asia, where long avenues of uniform specimens provide valuable shade.

Tall but relatively compact, few other species are so well suited to tough urban conditions: ginkgo is highly tolerant of atmospheric pollution, resistant to heat and drought, and appears better able to cope with compacted and poorly aerated soil than most other trees.

It survives winter temperatures down to at least -25°C (with reasonable tolerance of road salt run-off) and has no significant pest or disease problems. All things considered, the perfect street tree.

Well, not quite: ginkgo’s marble-sized hard seeds are surrounded by a fleshy outer seed coat that rapidly decomposes once the fruits drop in autumn. Fallen fruits produce butyric acid, a foul-smelling compound resembling rancid butter (or worse), making them an unpleasant nuisance on paved surfaces.

One solution is to plant only male clones that don’t fruit (e.g., ‘Princeton sentry’, ‘Autumn gold’). But here again, there is a catch: recent research indicates that ginkgo pollen may be significantly allergenic.

The extent of this allergenicity is still unclear, but specifiers should consider the possibility that massed plantings of male cultivars, or even single trees in enclosed precincts, could represent an environmental hazard.

Nevertheless, as one component of a varied urban canopy, ginkgo undoubtedly still has much to offer. Just be careful not to tread on the fruit!

This article was first published in the May 2024 issue of FloraCulture International. The author is Martin Deasy, a UK-based horticulturist and landscape designer.