It is usually in the latter days of September that the first sense of cooling relief descends on Tokyo as the enervating humid heat of the Japanese summer begins to slide into more hospitable autumn. However, it is also at this time of year that many Tokyo streets take on a decidedly less pleasant aspect when pedestrians cannot but be aware of an odor that might generously be compared with rancid butter—less charitably with, well, expelled matter that previously occupied a stomach.
The culprit behind the malodor is the yellow seed of the ginkgo, or maidenhair, tree, and it is the seed’s fleshy outer covering that exudes the insalubrious aroma. Though the smell does anything but stir the appetite, within that pulpy mass there lurks the delicacy of the ginkgo nut, or ginnan. The ginnan is not a true nut in the botanical sense, but it has a hard buff-colored shell that makes it not unlike a large pistachio. When cooked, the inner flesh turns a light pea green and has a nutty, slightly bitter flavor. Gathered in September and October, ginnan are essential ingredients in Japan’s autumn cuisine.
Japanese chefs typically prepare ginkgo nuts in simple ways. Ginnan are threaded onto bamboo skewers and roasted over charcoal in yakitori restaurants, which specialize in grilled chicken. In refined kaiseki cooking, ginkgo nuts are boiled or roasted, elegantly skewered on pine needles. Ginnan also appear in the classic savory steamed egg custard of chawan mushi.
The tree that produces the seedy nut goes by the scientific name of Ginkgo biloba, and it is the only living representative of a family that claims a history of 270 million years, which means that they predate the dinosaurs. The ginkgo is the oldest tree in the world, and it was Charles Darwin in his magnum opus, On the Origin of Species, who first referred to it as a “living fossil.” Despite its venerable lineage, this ancient tree thrives surprisingly well in the modern world and has no problem with the pollution of cities. Lines of the trees are a familiar sight along Japan’s urban roadsides.
As testament to their primordial origins, ginkgoes are rarities among trees in that they are dioecious: there are separate male and female plants. And it is the female of the species that produces the fruit that causes a bit of a stink.
Ginkgoes were long thought to be extinct in the wild, but the trees have now been found growing wild in a couple of areas in eastern China. However, the high genetic uniformity among these ginkgoes suggests that they were planted and preserved by Chinese monks over a period of about 1,000 years. In Japan, too, ginkgoes are often planted in the grounds of temples and shrines.
Before it was uprooted by a storm in 2010, Japan’s most famous ginkgo was one that had stood for 1,000 years in the precincts of Hachimangu shrine in Kamakura, close to Tokyo. One snowy February evening in 1219, the shogun, Minamoto no Sanetomo, was descending the steps after a ceremony at the place of worship, when from his place of concealment behind the great gingko tree an assailant emerged and beheaded the warlord. The assassin was the shogun’s nephew (among Japan’s nobility then, the waters of family love tended not to run too deep). And for his pains, the nephew was in turn beheaded shortly afterwards. But with his action, the powerful Seiwa Genji line of the Minamoto clan that had ruled Japan for almost 130 years came to an abrupt end.
The ginkgo playing its part at that decisive juncture makes for a good yarn. But it is alas the stuff of urban legend—the story detail of the tree was a concoction that did not appear until the Edo period (1603–1867). Though the ginkgo cannot claim its key role in Japanese history, it certainly has one in the present: in 1989, Tokyo chose the fan-shaped ginkgo leaf as its city symbol. And if Tokyo is successful in its bid to hold the 2020 Olympics, the world at large is likely to see a good deal more of its most ancient tree leaf.
David Capel is a journalist living in Tokyo.