Psst. Plants can kill you. Or at least try.

When I was eight years old, my sister and I discovered that a small tree in our Louisiana backyard was dropping some thickly shelled nuts into the grass. We loved  eating fallen nuts; an enormous pecan tree carpeted the front yard with them every summer. But these were different - rounder and fatter.
Curious, we smashed a few on a brick, opening up some fleshy pale kernels inside. "Almonds!" I proposed hopefully. We sat down under the tree and prepared a feast. I don't fully remember what they tasted like. Slightly bitter, a little like a fresh leaf, a blade of grass. We were always tasting plants back then - pulling up wild onions, sucking the nectar out of honeysuckle.

Our parents were hosting a rather special dinner party that night. My father, Murray Blum, is an entomologist and he had invited an old friend. E.O. Wilson of Harvard. I remember that my mother had a large colander filled with fresh shrimp in the kitchen sink, waiting to be slid into her special gumbo. And I remember the shrimp especially because I was sick all over them.

My sister, Darcy, was even sicker. As we kept retching up green material, our parents kept trying to find out what we'd eaten. We wouldn't tell them; we were afraid of getting in trouble. Finally, my father abandoned his dinner guests and went out in the backyard with a flashlight, discovering the remnants of our feast. He rushed back into the house to call the doctor in a definite state of panic.

The nuts we'd been chewing on came from a tung nut tree, known for its rather lovely heart-shaped pink flowers and the fact that a glossy oil can be pressed out of its nuts and used as a furniture polish. Donald Barceloux's  book, Medical Toxicology of Natural Substances, notes that the nuts seem to be more poisonous than the oil, which was not good news in our case.

I've not found a precise summary of the poisons in tung nuts, but they do contain phorbol esters (lacy compounds of mostly hydrogen and carbon) which are known to interfere with cell metabolism. And they also contain glycosides, organic compounds that contain sugar, and which include some dangerously toxic chemical groups, such as cyanide.

The toxins trigger such rapid and constant vomiting that their real threat is dehydration and severe electrolyte imbalance. Our family doctor in Baton Rouge, Louisiana told my parents to keep pouring hot sweet tea down the two of us and they did so all evening. With such treatment, medical reports suggest that most people people who eat tung nuts survive the experience. Obviously, we did or I wouldn't be writing this.

I did develop a healthy sense of caution about guessing the identify of plants that I might eat.  That's one reason I'm telling you this cautionary tale. Tomorrow begins National Poison Prevention Week and statistics tell us that accidental plant poisonings are still alarmingly common in this country - more than 60,000 a year. I plan later this week to focus on some of the most dangerous plants out there (and they'll surprise you).

And my second reason is a belated apology: Sorry about that dinner party, Mom and Dad!

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Dear Ms. Blum:
Judging from your interview April 2 with Science Friday's Ira Flato (sp?) on NPR--you have a boundless knowledge about your chosen subjects; however your remarking that cyanide is readily detectible in corpus delecti is not, in fact, so. See the Donald Harvey case here in Cincinnati (1987) wherein hospital orderly Donald Harvey used cyanide to kill the last of his victims and the assistant coroner (M.D. pathologist) nearly missed it as the cause of death. Finally, the "bitter almond" smell was the rub! But, as the assistant coroner told me in a lengthy interview (published in Cincinnati Enquirer's Sunday Magazine that fall): cyanide is NOT readily detectible. If one lacked medical training in pathology, its presence could be easily overlooked AND DISMISSED AS SUBSTANTIVE. Mind you, the coroner in this instance had received specific cyanide-detection training in medical school specialty. Psychiatrist Dr. Tondow, who did length analyses of Donald Harvey, told me that Harvey holds all-time record for mass-murder by way of poisoning his victims in hospitals. Over 50 known victims who died as a consequence of Harvey's in-hospital villainies!
Best Regards/Richard Harsham

By Richard Harsham (not verified) on 02 Apr 2010 #permalink

Hi, Richard - You raise some really interesting points - reminding me, and I hope everyone else, that doctors and coroners need better training in poisons. In fact, there's some great work from the 1920s which shows that cyanide ought to be readily detectable. That we find it difficult is a problem that we really should address. I'd forgotten about the Donald Harvey case and really appreciate the reminder. I'm hoping to do some serious writing about cyanide and take up some of the issues you've raised here. Thanks much for writing.