The gate, decorated with a large iron spider in a large iron web, creaked eerily on opening and then slammed shut behind me.
The spider signified the potential dangers that grew inside that garden, like Oleander (a glycoside). This innocent-looking plant can cause respiratory difficulties and heart problems. Although this Mediterranean shrub can be a fragrant addition to the landscape, every part of the plant is poisonous when eaten. The smoke is also toxic if plant parts are burned.
Other glycosides in the garden included foxglove and lily-of-the valley.
Why would a perfectly nice botanic garden include harmful plants among the others? For the same reason so many other plants are on display: to educate gardeners and the general public.
We can’t escape poisonous plants because they can grow anywhere. Jimson weed and nightshade; soapwort and poison ivy; stinging nettle and even St. Johnswort were a few of the other plants growing in the garden.
“A recent increase in herbal usage has given rise to misuse and mistaken identities,” explained a sign near the poison garden’s entrance. “It is important to consider means of preventing a toxic encounter as well as enjoying the contributions of poisonous plants around us.”
Because Halloween is a time for delightful frights, I recommend taking a read through Amy Stewart’s entertaining book called “Wicked Plants: The Weed that Killed Lincoln’s Mother & Other Botanical Atrocities” (Algonquin Books of Chapel Hill, 2009).
She includes poisonous plants familiar to most gardeners, like Castor Bean, Henbane, Hemlock and Deadly Nightshade. But she also includes some surprises like Habanero Chile, Sago Palm, Tobacco, Junipers and Bermuda grass.
“We assume if it grows out of the ground, a plant is natural and natural is good for you,” says Amy. But cyanide is also a natural substance that comes from some plants, and it definitely isn’t good for you.
Speaking of deadly plants, what do you think is the world’s most wicked plant? Scroll past the following poison plant resources section to learn the answer.
A nice addition to Amy’s book is a list of poison gardens throughout the world and a well-research bibliography with many poisonous plant resources and identification guides. Here are a few links to help get you started:
CSU’s Guide to Poisonous Plants database lists trees, shrubs and perennials that can be harmful to animals.
Cornell University’s College of Agriculture and Life Sciences has a searchable database of plants that are poisonous to livestock and other animals. The color images help with plant identification.
The University of Illinois Extension has a comprehensive list of links to poisonous plant information.
The World’s Most Wicked Plant?
By Jodi Torpey
Denver Master Gardener since 2005