You probably know the ginkgo. Maybe you’ve seen its fan-like leaves on streets of North American cities, smelled its pungent odor in the fall, or heard about it as a brain-boosting, memory-enhancing herbal supplement. In Chinese cuisine, you’ll see ginkgo nuts in congee and desserts, called the “white fruit” (白果). However, this “living fossil” was widely planted for its tolerance of pollution, compact soil, dry conditions, and other hardships of city life, rather than its uses in food and medicine, much to the surprise of many immigrants familiar with the taste and value of the nuts lying unwanted on the sidewalks. This bounty has led to the common spectacle of older men and women with bags and gloves (to avoid irritating chemicals in the flesh surrounding the nut) collecting the fallen nuts each autumn, some harvesting for home, some for selling to herb shops and at street stands.
From supplementing family income with nuts gleaned in public parks to providing stress relief the night before a thesis defense, ginkgo can help maintain ties between people, culture, and nature in cities.



Ginkgo is one of many “Urban Foraged” species. Another very popular street edible is the mulberry covered in an earlier post. Both are among the top three mentioned in a recent study within NYC’s Chinese American community, followed closely by mugwort and dandelion, and we also talked about serviceberry in Vol. 3 of #LEARNABOUT.

Gymnosperms 

Calling ginkgo “living fossil” is no exaggeration. Fossils dating back more than 270 million years from the Permian period have been found that are recognisably related to modern ginkgo, and that’s 40 million years before dinosaurs even existed.
Because ginkgo is such an ancient species, it is not at the ultimate form in plant evolution. Ginkgos, along with pines, yews, firs, conifers, spruces, cedars/junipers, cycads and palms, belong to a group of plants called gymnosperms.


Gymnosperm means “naked seed,” and it has gained a significant evolutionary advantage over its predecessor, ferns, which uses actual mobile sperms to reproduce and whose fertilization is dependent on water.
By using seeds to reproduce, gymnosperms eliminated the dependency of water in its reproduction cycle, and therefore adapted better to dry climates.
However, at this point in evolution, one important organ has not emerged yet: flower. Furthermore, a part of the flower, called ovary, which usually encloses the ovules (that develop into seeds), hasn’t emerged either. Therefore, gymnosperms also lack fruits.
The group of plant that reached the summit of plant evolution is called angiosperms. They are also called flowering plants for the very reason. All angiosperms have flowers and fruits, despite whether you have seen them or not. Have you seen the flower of figs or wheat? Maybe not, but trust us, they exist.

Ginkgo biloba the survivor

“Biloba” means two-lobes, and you will know exactly what it means if you have ever seen a ginkgo leaf.
#insert ginkgo leaf here
Ginkgo biloba is the only species left out of the once existing dozen ginkgo species. Fossil records have been discovered of some ancient species that are very very similar to modern ginkgo leaves, and some not so similar at all.

We do not know how all of the other ginkgo species have gone extinct, but we do know how ginkgo biloba survived, and we have to thank the monks in northern China.
Ginkgo was (re)discovered by Engelbert Kaempfer, who was with the Dutch East India Company at their trading station in southern Japan in 1692. The tree had a Chinese origin, and it was later discovered that the Chinese monks in China have preserved these trees for more than 1000 years for their symbol of longevity, the beautiful leaves, and the medicinal utilities of the seeds.
The other reason of ginkgo’s survival is due to its extreme resilience to harsh environments. After the atomic bombing on Hiroshima on August 6th, 1945, a ginkgo tree was found located 1.1km away from the epicenter, next to a temple, and had begun to bud despite the blast a few months later. The temple, however, was completely destroyed and had to be rebuilt in 1994.
Ginkgo trees now grow all over the world as "street trees" for their ornamental look and its ability to tolerate urban environments, absorb pollutants, and increase air quality.

Aril (not your little mermaid)

We told you that gymnosperms don’t have fruits, so you may ask: what the heck is the orange-yellowish flesh surrounding the seed then?!
The flesh that surrounds the ginkgo seed, as well as the red flesh surrounding the common yew, is biologically called an “aril,” or “arillus,” which derives from the stem, not the ovary. Since it resembles a fruit so much, it is sometimes called “false fruit.”
There are a few cases of angiosperms that have arils too. The common examples are: longan, lychee, nutmeg, even dandelions.


It is no secret that the fleshy aril of the ginkgo smell bad. It smells like vomit of some half-digested pungent cheese.
The foul smell comes from a compound called butyric acid, also known as butanoic acid. Butyric acid is present in, and is the main distinctive smell of, human vomit, and I guess that explains why ginkgo arils smell so. However, butyric acid is known to have numerous beneficial effects in humans on energy homeostasis and related diseases (e.g., diabetes and obesity), immune function, and inflammation, which mediate its antimicrobial and anticarcinogenic properties.

Sexism not, dioecy

Curiously, ginkgo trees actually have genders. Such phenomenon is called dioecy (meaning “two households”) in plants, which male and female trees grow on separate plants. The male ginkgo bears no fruit, and therefore no smell (and therefore recommended by many states and cities to grow instead of femails). The female ginkgo trees will fruit every fall, flauting its acrid and malodorous “fruit” of its reproductive success.
Dioecy also exists in angiosperms.  Willows and cannabis are some notable examples.

Leaf art

The leaves of ginkgo leaves turn bright yellow at fall, and both the green leaves and yellow leaves dry very well, which make them prime candidates for making pressed leaf art. Experiment with the compositions and lovely fan shapes to make a collage!

Identification 

As unique as ginkgo is, here are some extra identification tips to make sure you’ve got the right tree:

• Fan- or fishtail-shaped leaves that turn golden yellow in autumn and have parallel (rather than branched) veins
• Often a straight/centralized branching structure with branches forming near right angles with the main trunk
• Branches with short nubs where leaves emerge

Word of warning

Besides congee and desserts, the football-shaped nut has to be roasted to a beautiful jade green for snacking, though many a wary forager has warned and been warned not to eat more than ten in a day. Seeds and leaves of the ginkgo both contain ginkgotoxin, a compound that in excess can cause seizures (and even death) by disrupting vitamin B6 metabolism and creating imbalance between inhibitory and excitatory neurotransmitters. Ginkgotoxin can be about six times more concentrated in seeds than in leaves.
However, if you’ve already devoured your harvest and are now panicking about your mortality, no need to call your loved ones to say farewell! Reactions to ginkgotoxin vary widely and any sign of poisoning can be relieved by taking B6 supplements.
It is also advised that you eat the ginkgo seeds when fully ripe, you can identify fully ripe sees by judging if the aril turns orange/yellow and emit that pungent smell.
If the aril of the seed is still green, do not eat the seed. The picture below shows unripe ginkgo seeds and arils.

Where can I buy them?

If you don't know a local forager and you aren't up for dealing with the foul smell on your own, you can also buy ginkgo seeds from Asian grocery markets. They usually are labeled "ginkgo nuts" and come in either raw forms, or shelled shrink-wrap packages, or cans. The raw ginkgo seeds look like unopened pistachios.

How to eat ginkgo seeds

• Eat them on their own, but make sure to roast/boil them, or pop them in the microwave oven 
• Add the cooked ginkgo seeds to salads, congee, soup, porridge, rice, or wherever you would want some fantastic nutty flavor 
• Traditionally goes in porridge with longan, jujube, lotus seeds, silver ear mushroom. I know, lots of foreign names, but don't worry, we will cover them all someday. 
• It goes extremely well with poultry. 
• Here's a picture of Matsutake Gohan (mushroom rice) with ginkgo seeds from the kitchn. 

Flavor Index

Ginkgo seeds have a nutty bittersweet flavor and a soft starchy texture reminiscent of jelly beans (minus the stickiness).


(image sources: fossilized ginkgo leafs: http://smithsonianscience.si.edu/; ancient ginkgo tree: http://www.yicai.com/images/2015/11/4715614.html; ginkgo nut raw: http://www.smc360.com/Product/ProductDetails.aspx?id=1623; ginkgo nut shrink wrap: http://nkit.org/Cookbooks/CoreanCookbook/glossary.htm; ginkgo nut can: http://victor.iwi.com.sg/gjh/Products.aspx?productCatId=22; Matsutake Gohan: http://www.thekitchn.com/cooking-japanese-matsutake-goh-108656 )