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Poison Posies


Tags: plants, poison, edible, toxic

Created: 2/27/2013      Updated: 8/10/2016

If you visit the museum during the growing season, you’re likely to find me out on the grounds somewhere looking quite dapper in dirt-stained pants and a wide brim hat, a stalk of foxtail grass dangling from my lip. Or you might catch me pausing, rake or shovel in hand, to pluck and nibble on hackberries, purslane, or wood sorrel. City folk (I’m allowed to say that because I spent my first thirty years of life in West Virginia) often give me strange looks. Some even feel compelled to remark upon my behavior: “You shouldn’t be eating that.” “Don’t put that in your mouth, you don’t know where it’s been.” “What if a dog peed on that?” Or the always attention-getting, “OH MY GOD THAT’S POISONOUS YOU’RE GOING TO DIE!!”

At this point, I politely explain that I’m a horticulturist, so knowing which plants are nummy and which might leave one “in repose” is right in my wheelhouse. In other words: Trust me – I’m a professional.

Interestingly, people who aren’t in the know often assume plants to be more dangerous than they actually are.*  While a decent percentage of the 250,000 described plant species will send one running to the nearest restroom if consumed in quantity, only a few dozen are known to be toxic enough to truly be considered deadly.

In our area, plants of the genus Cicuta (commonly known as water hemlock or cowbane) are among this group. Ingesting even small amounts of the roots can result in a long list of nervous and cardiac difficulties, including that most incurable of symptoms, death. In some sort of sick, cosmic joke, water hemlock fairly closely resembles the edible (though disappointingly tough and fibrous) wild carrot. Now would be a good time to reread that first asterisk at the bottom.

Other nasties that grow wild in our area include Doll’s Eyes (Actaea pachypoda), Canada Moonseed (Menispermum canadense), and Black Nightshade (Solanum nigrum). But if you really want a “who’s who” of plants that can kill you, look no further than your local botanical garden. There, you’re almost certain to find Monk’s Hood, Foxglove, Oleander, Delphinium, Autumn Crocus, Laburnum, Yews, Privets, and Azaeleas.

In fact, your local botanical institution is quite possibly, at this moment, in posession of two of the deadliest substances known to exist. The Castor Bean (Ricinus communis) and the Rosary Pea (Abrus precatorius) are both widely grown – the former as an ornamental and for the production of castor oil, the latter for its decorative seeds. The seeds of these plants contain small amounts of two astoundingly toxic protiens – ricin and abrin, respectively. According to the European Food Safety Agency, a mere 3 milligrams of ricin is enough to kill an adult human. Pretty impressive. But only until you find out that abrin can kill at doses 150 times lower**.

Rosary pea, poisonous, and Western Water Hemlock, poisonous       

Believe it or not, my point is not to frighten you into never touching a plant again. Deaths from plant poisoning are exceedingly rare in the US. (One study I found counted 30 deaths in 18 years, some of these cases involving attempted recreational use of plants such as Jimsonweed.) Compare that to the average 50 or so lightning deaths per year and you start to get the idea: Experimenting with wild edibles is a pretty safe pastime. A good way to start is to learn the bad guys by heart. Because fortunately, scary though they are, they are the exceptions. And next time you see me outside the museum, ask me what I’m eating.

*A message from the nice man with the briefcase and the power tie looking over my shoulder: Don’t eat any plant you do not know to be edible or cannot positively identify.

** Dickers et al, Toxicological Reviews, 2003 - Volume 22 - Issue 3

Seth Harper
Museum Horticulturist

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