Lily of the Valley (Convallaria majalis). Pretty, delicate, toxic. Image credit: Leo-seta.
Sadly, the internet tells me that there’s no such thing as a toxophile or toxicophile. If there were, I’d make a blog button for it. (Other suggested blog buttons for my site: Anti-Social Media Expert — thanks, Karen — and Evolutionary Dead End. Alas, I don’t know how to make buttons.) Anyway, what I mean to say is that I kind of have a thing about poisons. And by thing, I mean that people who look too closely at the books on my bookshelf might decline an invitation to dinner.
This is what comes of reading too many Agatha Christie books at a young and impressionable age.
Plant poisons are my favorite. I’m always taken aback by how elegantly and creatively nature addresses the problem of being eaten. Plants can’t run, so instead they wage chemical warfare on their predators. The Indian bean tree, for example, produces a nectar with a compound that only affects cheater species that steal nectar — but not pollinators.
And plenty of plants are well-protected not just against insects, but also bigger animals, like humans. There are lots of them, and they’re all around us. I’ve pulled together some of my favorite common wicked plants, a number of which are probably in either your backyard or a backyard near you. Welcome to my virtual poison garden!
(And for crying out loud, teach your kids to respect plants. I sampled my way through my mom’s garden as a kid and got lucky she didn’t have anything really poisonous. Although I guess that could explain some of my peculiarities.)
Nerium oleander. Image credit: heatheronhertravels
Oleanders are, in a sense, perfect garden shrubs. They’re drought resistant, have nice foliage, and produce lovely symmetrical pinwheel flowers that smell nice. They’re also among the deadliest of common garden plants, possessing a number of cardiac glycosides that affect heart function and can cause death. Even honey made from oleander nectar is toxic. (Most deaths by oleander, however, are intentional. By anecdote, a number of seniors have ended their lives by drinking oleander tea because it was readily available in their nursing home garden. That story makes me sad.) Interestingly, oleanders are also being investigated for therapeutic uses in treating cancer. The dose makes the poison.
Viburnum lantana. Image credit: Bosc d’Anjou
Lantanas have peppy colored flowers and nice leaves, but that’s about where the good news ends. They’re invasive in Australia, Hawaii, South Asia, and Southern Africa because 1) birds like the fruit and spread the seeds; and 2) the leaves are toxic to most species. Lantanas, especially the unripe berries, contain pentacylic triterpenoids that cause liver problems and phototoxicity in grazing animals (including small children).
Digitals spp. Image credit: Salt Spring Community
Foxgloves are an old garden favorite. The name has an odd etymology that doesn’t actually involve small reddish quadrupeds (Wiki can tell you all about it). Another name for this plant is deadman’s bells. Foxgloves contain cardiac glycosides and have actually been used to treat some heart conditions since the 18th century. My grandmother, who has had congestive heart failure, is on a synthesized form of digoxin. However, cross the [narrow] therapeutic threshold and foxgloves can cause nausea, halos, delirium, irregular heart rhythms, and death. All parts of the plant are toxic, not just for humans, but also for dogs and cats. Even drinking the water that cut foxgloves are sitting in can be deadly.
Conium maculatum. Image credit: jkirkhart35
I doubt anyone plants poison hemlock on purpose, but it’s a common weed in fields and pastures. It’s quite a delicate looking plant, a spindly 6′ tall with dainty little white flowers. Purple spots or streaking on the stalks are a dead giveaway, but it resembles plants that are edible or medicinal (Queen Anne’s Lace, wild fennel, parsley. Socrates is probably hemlock’s most famous victim. Hemlock contains a highly toxic compound called coniine, which paralyzes the muscles, including the heart. It doesn’t take much to cause death — 100mg of the leaves, root, or seeds.
There are many, many others: nightshades, sago palms, castor bean, angel’s trumpets, water hemlock (as if one deadly hemlock weren’t enough), buttercups, dieffenbachias…just more proof that nature’s chemicals aren’t necessarily safer than manmade ones. Which poisonous plants do you have in your garden?
OK, I think I’m done poking my naturalistic fallacy in the eye with a sharp stick now. If you’re interested in the topic, you might enjoy:
- Wicked Plants by Amy Stewart
- Handbook of Poisonous and Injurious Plants by Lewis S Nelson, Richard D Shih, and Michael Balick
- The Poison Diaries by Colin Stimpson
- The Poisoner’s Handbook by Deborah Blum (not plant toxins, but a great read)
