Wicked, wicked plants

The handsome, but poisonous, castor bean plant. — M Fletcher/Flickr

The handsome, but poisonous, castor bean plant. — M Fletcher/Flickr

Some plants lure us into a false sense of security by sitting there looking pretty. Others live sordid lives of foul behavior, employing nefarious means to defend themselves and extend their dominion.

There are trees that blind, weeds that blister, shrubs that sting and bulbs that kill. They’re armed and they’re dangerous – trifle with them at your peril.

Behind every horticultural miscreant is a story, though, and that makes them dear to author Amy Stewart. Her book “Wicked Plants: A Book of Horticultural Atrocities” (Algonquin Books) spreads the word about the dastardly deeds of her subjects.

“The plant kingdom has a lot of power and we should acknowledge and respect that,” says Stewart. “But I personally love a villain, and love the drama and suspense of fateful encounters between people and plants through history. My message is not just a warning to stay away from this or that, but an invitation to enjoy the wicked and creepy side of plant life.”

Stewart’s book is organized around a “list of offenses” and offers some 200 examples of plants that are deadly, destructive, dangerous, painful, intoxicating or just plain illegal. Paging through her book is like shuffling a deck of Tarot cards, with potential harm and threat on every page.

Meet the poisonous caster bean, with seeds so deadly that three of four can kill an adult human. It’s also the source of rincin, a toxin used in terrorist attacks. Or how about Jimson weed, responsible for the gruesome deaths of Jamestown settlers in 1607? Or aconitum, a beautiful flower, poisonous in all its parts, that stops the heart?

Most people are aware that having the wrong sort of mushroom for dinner could make that meal their last. But the bulb of the aptly named death camas, a flower of western American meadows, can bring on fatal seizures and coma. And deadly nightshade, an herb of damp woods, produces toxic berries that killed 49 Turkish children in one six-year period.

Fruit of the manchineel tree. — Jason Hollinger/Flickr

Fruit of the manchineel tree. — Jason Hollinger/Flickr

Even plants we welcome at the table can harbor harmful secrets, as Sonal Bhatt, BBG’s director of interpretation and exhibitions, has pointed out.

The fruit of the tomato is an ambrosial treat of summer, but its leaves and stems are poisonous. Likewise, the tuber is the sole edible portion of the toxic potato plant, and even it should be discarded if it begins to turn green, indicating a build-up of harmful solanine.

“The thing is, it’s not all about us,” Bhatt says. “Plants have amazing adaptations that help them fend off predators or survive in a nutrient-poor environment by trapping and digesting insects, as carnivorous plants do.”

In idyllic tropical vacation spots, beware of potentially injurious plants of the itchy kind — mangoes and cashews, which are related to poison ivy and in the same family as poison sumac. Highly allergic people should avoid all of the above.

The manchineel tree, America’s deadliest, is found in Central America, the Caribbean and south Florida. It is so toxic that experts warn not to eat the fruit, touch the trunk or leaves, stand under it in a rain or even inhale the air near it other than briefly. An arrow tipped with manchineel sap is said to have been the death of explorer Ponce de Leon. And yet, we welcome a related plant, the poinsettia, into our homes for the holidays.

The takeaway here is that plants are not always passive and some can be physically dangerous to humans and other living things. At least in some small way, you have to admire a plant that faces the world with attitude. But one should not blunder blindly through jungle, meadow or forest.

And please! Don’t eat the daisies – or the berries, roots or leaves of strange plants -- in the garden or the wild.