Hikers, anglers and other outdoor enthusiasts are urged to keep an eye out this spring for an elusive plant that may be staging a comeback. The so-called stinging rejoinder, Aculeatus depulsio, although it is a distant cousin of stinging nettle, Urtica dioica, does not actually sting or cause a rash. It is an inconspicuous, native medicinal plant which was over-harvested in the 19th and early 20th centuries, and has been hard to find since that time. However, there is indirect evidence its population could be on the rise.

Its common name comes from the way Aculeatus depulsio works on the nervous system. When taken internally, the stinging rejoinder seems to temporarily inhibit neuronal reuptake of glutamate, an excitatory neurotransmitter, in the frontal cortex. In plain English, it makes you smarter for a short time, which explains its popularity. It does lose potency quickly, though, and must be used fresh.

Because it disappeared before the advent of giant pharmaceutical companies, its active constituents were never isolated or identified. Had they been, you can bet your wallet they would be patent-protected and would cost a fortune today. As with all herbal remedies, always consult your health care provider before using Aculeatus depulsio, because herbal medicines can aggravate certain conditions and/or interact with medications.

Unfortunately, Aculeatus depulsio looks similar to a lot of other plants, and over the years many people who thought they had found a good stinging rejoinder were disappointed when they tried it but it had no effect. Aculeatus depulsio leaves are slick-looking, glossy and inviting, but dark; almost always pointed, and occasionally barbed. Its stem has formidable-looking thorns, which often turn out to be harmless. It can reach anywhere from a few inches tall to about six feet, but inevitably winds up being much smaller up close than it looked from a distance. The plant is found in wet, unstable ground, and there exist scads of old anecdotes about people sinking deeper and deeper in mire searching for one.

Aculeatus depulsio was traditionally used to enhance cognition during arguments, especially those in the context of committed relationships, by one or both parties. It was considered unfair to use preemptively, though this cultural norm was sometimes ignored. Especially in cases where one party had betrayed the trust of the other or been needlessly harsh, the injured party might seek out Aculeatus depulsio to make a particularly salient rebuke.

Occasionally this would work to devastating effect, but more often than not it would end up being a waste of time. Statistically speaking, most arguments occur at night. But for some reason, the stinging rejoinder is more easily located the following morning, when it may no longer be useful or even desired.

Botanists speculate that Aculeatus depulsio numbers may be up, pointing to recent studies which show snappy retorts are on the rise. Sociologists, on the other hand, point out this is only the situation with the younger demographic, and they maintain that social media and “argument Apps” on mobile devices are behind this new trend. Only time will tell.

In the meanwhile, please be on the watch for stinging rejoinders when you’re in the great outdoors this spring. Documents dating back to the late 1800s indicate the best day to seek out the rare Aculeatus depulsio is the first day of the fourth month. Happy April Fools’ Day, everybody!

Photo: Close relative stinging nettle (photo by Uwe H. Friese).