The Maidenhair and Mr. X

My March 2025 essay was entitled GARDENING INJURIES: OUCH or worse! Near the end of that piece I very briefly discussed allergic reactions. Mind you, one could do books on the topic as there are lots of unrelated plants that can cause some sort of immune response, as well as considerable individual susceptibility and various contributing factors. This month I will describe a specific example but need you to understand that I am doing so in the context of another topic -- considering the full profile before jumping to the conclusion that "you must have it" or "that you will believe it." Too often that is exactly what we do. That is, we let one or more attribute blind us (e.g., sure is pretty or sounds good) -- thus preventing us from making an informed (wise decision) -- and we often seem to be as reluctant to verify and/or to address the mistake once (if ever) we know better.

Now on to our story. We will start with the allergen.

One of the most interesting woody plants you will ever encounter is Ginkgo biloba (AKA ginkgo or maidenhair tree). This ancient and unique plant is the only extant species in the genus. In fact, it is the only living member of the entire family. A relic from times past, G. biloba has existed virtually unchanged for over 200 million years. Its ancestors knew T Rex and the pterosaurs -- literally a living fossil. Yet, while once globally widespread, ginkgo has been extinct in nature for centuries, although there might be rare wild survivors in China's phenomenally plant-rich SW mountainous regions. We still have ginkgo (i.e., its extant) thanks to its usefulness but especially its association with shrines and temples of oriental (Eastern) religions. Ginkgo, which is potentially huge (15+ ft diameter) and long-lived (1,000+ years), is a pollution tolerant tree species common in urban landscaping. Moreover, the species has considerable morphological plasticity. Many unusual and spectacular leaf forms are available, including some with variegation as well as long thin leaf lobes. The variably cleft fan-shaped leaves are produced on short spur-like branches (see pic), turn a stunning gold in fall and bizarrely often almost all fall off (abscise) within a few hours -- at my place in NE Indianapolis, most likely in the AM on November 9th (see my ALMANAC).

But what many people do not realize is that the beautiful ginkgo has a sinister side. The female plants, once they are mature, produce clusters of a fruit-like structure on a long stalk (peduncle). The round fruit-like structure resembles a drupe (i.e., a fleshy portion surrounding a single hard-cased seed), something like a plum, but the "fruits" are technically not since ginkgo is a type of gymnosperm, which literally means producer of "naked seed." The individual "fruit" are about one-inch in diameter, start out green but transform to tan-yellow-orange (apricot like) and have a very thin skin. It takes but little pressure to break, to expose the moist pulp. The seed casing is somewhat flattened with a distinct encircling ridge (suture), sometimes more than one, and resemble an oversized pistachio (see pic). However, unlike pistachio, the ginkgo "nut" is not dehiscent (i.e., does not naturally crack open).

This is where the unfortunate story of a friend of my youngest daughter and her beau (Mr. C) comes into play. The friend (who I will refer to as Mr. X) was walking to a local bar to watch football on a hot day in mid-September (2025) when he and his partner came to a ginkgo branch that had snapped and fallen onto and across the sidewalk, thus blocking their way, in the residential DC neighborhood they were passing though. The ginkgo was female, the blocking branch was heavy with fruit, and the ground beneath it was covered with the fruit, too. Mr. X, who was wearing shorts and sandals, stepped over the branch and in so doing he inadvertently squished some of the pulpy fruit, with some of the pulp getting on his right ankle and lower leg. He wiped the pulp off using a nearby dead leaf (he doesn't know what kind), and they proceeded to the bar for his football fix. Upon arriving back home a few hours later he showered and thought nothing more of the incident. About a week later he noticed that the skin on that leg (below the knee) was turning red and starting to itch, like with a poison ivy reaction. Yet another week later blisters started to form (see first pic below) and he decided it was time to see a physician. The doctor prescribed antibiotics, burn ointment (see last pic) and sterile wrapping. Mr. X said it took a month for the condition to go away and he still has a scar on his ankle which had become quite swollen during the ordeal. Curiously, his partner did not develop the rash or blister (she may not have gotten the pulp on herself), nor did Mr. X develop the rash or blister on his pulp removing hand or any other part of his body.

Ginkgo is unisexual (dioecious), but one will not know an individual ginkgo tree's sex until it is mature (i.e., shows its sex by producing the delicate staminate {male} or pistillate {female} cones in spring). On average it takes as long as 20-30 years or more for that to happen. The sexes are morphologically identical except for the cones and and "fruit." And ginkgo, like some fishes, can change sex if need be! It's called sequential hermaphroditism -- a natural form of transgender. Furthermore, I waited to tell you that the ginkgo "fruit" pulp stinks (something like a cross between dog poop and vomit) due largely to a substance called butyric acid. Related (see my Collective Nouns link) a group of these is referred to as a stink-o of ginkgos :) Yet the seed inside the nut is edible and considered a delicacy, having first been de-pulped and then roasted. I have witnessed the stinky things being collected, with those doing so wearing rubber gloves to prevent the same problem that Mr. X suffered. The reaction is caused by compounds including one very similar to urushiol (the oil found in poison ivy and unprocessed cashews). Interestingly, cashews are related to PI (i.e., in the same plant family, Anacardiaceae). While about 85% of the general human population are allergic to poison ivy (develop contact dermatitis), to some degree, similar susceptibility to ginkgo pulp is much less common (evidently only 1-10%), but it can be severe. As Mr. X can attest.

Yes, ginkgo is wonderfully strange and physically appealing BUT, if it is yours or in a public setting, at the first sign it is a female, a chainsaw is what I would recommend. Yet it is common to encounter walkways in the fall literally covered with this fetid, messy and dangerous pseudo-fruit, and the owner could be liable. And, as I noted earlier, we are reluctant to admit or address a mistake -- gardening and life in general -- but quick to judgment without knowing, as Paul Harvey used to say [pause] "the rest of the story!"