COMMON MAYAPPLE: Devastate your rival's intestines with Podophyllum peltatum. Eric Hunt, Arkansas Native Plant Society

If you’re plotting to murder your enemies but hoping to go the naturopathic route, Arkansas is an opportune place to be. Look out the window and you’ll likely put eyes on flora that, when rubbed on the skin or ingested in adequate quantities, can bring on punishing effects ranging from mild rash to deadly cardiac arrhythmia. 

We also have the expertise on the ground to pull it off. Steven Foster, an author, photographer and master herbalist in Eureka Springs, is an expert on medicinal plants. Co-author of a “Peterson Guide to Venomous Animals and Poisonous Plants” and photographer for the “Handbook of Poisonous and Injurious Plants, Third Edition,” Foster is the rare writer whose content fits equally well at Barnes and Noble as Flourish and Blotts. 

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His interest in herbology first bloomed on a walk to school, when he asked a friend about a trillium he saw in the woods. “She said, ‘My grandfather calls it “stinking benjamin” and they use it as an aid in childbirth.’ At that moment I said, ‘Oh, I want to learn the names and uses of all the plants.’ And so, 19 books and 47 years later, I’m still learning the names and uses of all the plants.”

Foster uses his powers only for good, sharing decades of knowledge about dangerous plants to help people avoid getting sick or worse. But it’s Halloween, and if you’re itching to boil up a potion or two, what can we do about it? You’re obviously free to use this information however you like, be it cautionary or instructive.

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Eric Hunt, Arkansas Native Plant Society
YELLOW JESSAMINE: One nibble of Gelsemium sempervirens can send you to the next realm.

Please note that this list is far from exhaustive. Arkansas is apparently so packed with dangerous plants that “there are too many to mention them all,” Foster said. But there are about a dozen that can induce a forever dirt nap fairly easily. The key thing to remember for pretty much all potentially problematic plants, Foster said, is that “the dose makes the poison.” A nibble of something might be harmless, but a cupful could do you in. “It really depends on how much you eat or take,” he said.

Take pokeberries from the pokeweeds ubiquitous along Arkansas roadsides. They’re known to be poisonous, but they’re also purple and juicy and look far more appetizing than, say, a Tide pod. So it’s no wonder children snack on them sometimes, necessitating a trip to the emergency room. Usually, Foster said, those kids are fine. That’s often not the case when people incorrectly prepare the leaves of that same plant for the Southern classic dish of poke sallet. The leaves have to be cooked twice, using fresh water each time, to boil away the toxicity. Otherwise, vomiting and convulsions can result.

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Eric Hunt, Arkansas Native Plant Society
POKEWEED: Phytolocca americana makes a tasty poke sallet, but beware.

Like those shiny, pretty pokeberries, the late-winter blooms of yellow jessamine can prove irresistible to the young and curious. Parents, beware. “Those flowers contain an alkaloid that can have a deadly impact on the heart,” Foster warns. “There are fatalities attributed to children eating as little as one flower.”

Some of the deadly plants growing in Arkansas soil arrived uninvited. Foster calls such plants “noxious weeds” and “invasive aliens,” and is clearly put out by them. He blames Christopher Columbus. “I don’t think of Columbus as discovering America,” Foster said. “I think of Columbus as initiating the cross-cultural transoceanic spread of plant propagules.” 

STEVEN FOSTER
POISON HEMLOCK: It killed Socrates, and Conium maculatum can kill you, too.

One such propagule is the poison hemlock that arrived in the New World from Europe and Northern Africa, possibly brought by witches; there’s really no way to know. Not that anyone would want to do this, but you could reenact the poisoning of Socrates using this particular ingredient that may well be growing in your yard right now. Poison hemlock is “a rank weed with carrot-like leaves,” per Foster’s disdainful description. Unlike the evergreen hemlocks that grow in the Pacific Northwest, the hemlocks in Arkansas, Conium maculatum, belong to the carrot family. “We have lots of it here. It comes up in the spring and it will get these large, fern-like leaves,” Foster said. “They have a rank smell and the stems have purple spots. The seeds and the roots are especially toxic.”

Each spring Foster notices a patch of poison hemlock along the road from Eureka Springs to Berryville, reaching heights of 7 to 9 feet. “There’s a half-mile stretch with a wall of poison hemlock along the road in the springtime, which is a little scary,” he said.

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Eric Hunt, Arkansas Native Plant Society
CASTOR OIL PLANT: This landscaper’s darling, Ricinitus communis, is a go-to favorite for KGB assassins.

The castor oil plant, far more lovely than its name lets on, is an ornamental that’s not native to Arkansas, but is often used in landscaping. These plants are also the source of ricin, the poison an assassin famously loaded into the sharpened tip of an umbrella and fatally jabbed into the leg of a Bulgarian dissident in London in 1978.

Less showy but equally deadly is white snakeroot, a small and relatively nondescript plant with tiny white button flowers that took down Midwestern settlers by the thousands in the 19th century. Unbeknownst to them, white snakeroot contains tremetol, a toxin that causes trembling, vomiting and severe intestinal pain in people who drink milk or eat meat from animals that grazed on it. The affliction is called milk sickness, and it killed Abraham Lincoln’s mother.

ERIC HUNT, ARKANSAS NATIVE PLANT SOCIETY
WHITE SNAKEROOT: The end of the trail for thousands of westward settlers, Ageratina altissima causes the dreaded trembles.

The adorably named common mayapple is another plant whose innocent appearance belies a propensity to wreak havoc on human bodies. These sweet-looking flowers huddled beneath umbrellas of star-shaped leaves harbor the nastiest of secrets. “The root is not deadly toxic unless you took way too much of it,” Foster said, “but it’s strongly laxative. Like, cathartic, purgative laxative.”

Tinkering with medicinal and poisonous plants can be an art as much as a science, and there’s often no way to know how one person’s biology might react. Foster himself has personal experience with this. Six years ago an herbalist friend gifted him with honey candies infused with edible hawthorn berries. The berries are often sold in supplement form, and have long been used to regulate heart rates. But how much is too much? “I was eating them like peanuts,” Foster said. That night, he suffered shortness of breath and a feeling that something was wrong enough with his heart function that medical attention was in order. By 11 a.m. the next morning, he had a new pacemaker installed. “That just shows you how easily somebody can make a silly mistake with a plant.”