“A tree sheds poison daggers; a glistening red seed stops the heart; a shrub causes intolerable pain; a vine intoxicates; a leaf triggers a war. Within the plant kingdom lurk unfathomable evils,” writes author Amy Stewart in her most recent New York Times bestselling book, Wicked Plants: The Weed That Killed Lincoln’s Mother & Other Botanical Atrocities.
To complete her preliminary research, Stewart visited gardens, including Cornell’s own Poisonous Plants Garden, located adjacent to the veterinary school.
Stewart also visited Duchess of Northumberland’s poisonous plant garden located outside Northumberland castle in England, made popular by its appearances in the Harry Potter films as Hogwarts Castle. The Duchess’ garden is home to many “wicked plants,” like cannabis sativa, or marijuana. Because marijuana is illegal in England, the keepers of the garden needed to obtain special permission to grow it in a padlocked cage.
At England’s Chelsea Physic Garden, founded in 1673 as an apothecary, Stewart examined Castor Bean, Strychnine and the Cola Nut – each capable of killing almost instantly. For example, Ricinus communis, or Castor Bean, is a perennial shrub with deeply lobed leaves, prickly seedpods and poisonous seeds. The seeds contain ricin, and ingesting as few as three seeds can kill a fully-grown man.
On another trip, Stewart visited the USDA Poisonous Plant Research Laboratory in Logan, Utah.
According to Stewart, the lab started out as a small facility created to help ranchers determine the value of livestock feed, but now deals with other research. Their research is making a significant difference for children born with cleft palettes.
“Ranchers figured out that their goats were grazing on some kind of plant that was causing them to give birth to kids with cleft palettes. They called the folks at the USDA, and they figured out that it was Nicotiana tabacum, or tree tobacco. They graze on this during a very narrow time during their gestation period and this causes the deformation.”
A team of surgeons from Providence experimented on pregnant goats to develop a way to correct cleft palette in the womb.
“The surgeons were able to develop a technique where they cut open the mama goat, cut into her uterus, and correct the palette. The goat then continues to carry the baby and eventually gives birth to a completely scar-less baby goat.”
The surgeons also allowed some goat kids born with cleft palettes to test corrective appliances that could be used on humans.
One of the most painfully wicked plants, the Giant Stinging Tree of Australia, is covered with tiny little fuzz-like hairs. “But if you look under a microscope,” Stewart explained, “they are more like needles with a tiny and potent dose of a neurotoxin.”
Basically impossible to pull out, the needles cause pain that is “the worst stinging ever imaginable,” Stewart said. The pain can last up to a year, and can return due to heat from sunlight or a hot shower.
“The only solution, which doesn’t even always work,” Stewart explained, “is to use a waxing strip and try to wax the needles out.”
Stewart described Caulerpa taxifolia, or Killer Algae, as “more creepy than wicked.” While most algae can’t handle the cold temperatures of the Mediterranean Sea, this species is unusual. It was discovered in Stuttgart, Germany, in an aquarium with Mediterranean fish.
Aquarium staff around the world wanted to experiment with this “creepster,” and the killer algae soon made its way into the wild when an employee tossed waste into the sea.
This plant isn’t deadly to humans, but it contains caulerpenin, which is toxic to fish. Because the plant reproduces through propagation, it spreads rapidly after it is cut. “Attempts to eradicate it haven’t met much success, because chopping it up only helps it reproduce,” Stewart said. “One of the few success stories comes from San Diego, where an eleven thousand square foot patch was destroyed by placing a tarp over it and pumping chlorine into it.”
Stewart’s A to Z list of wicked plants also includes common yet dangerous houseplants. Lilies, for example, can cause liver failure in cats; the cat may die within two days. A ficus tree is dangerous as well, causing allergic reactions with itching and swelling to anaphylactic shock and death.
Despite the dangers, however, Stewart doesn’t think “running home and throwing out all your plants” is a good idea. “Go into your bathroom and you’ll see conditioner and shampoo and shaving cream,” Stewart said. “You know not to eat them. It doesn’t mean you should be terrified of them - you just shouldn’t have them for breakfast. The same is true for some of these dangerous plants.”