Lovely but Lethal: How Well Do You Know Your Toxic Plants?


By: Torrance Grey

6 Min Quiz

Image: Shutterstock

About This Quiz

Who knows what dangers lurk in your backyard garden or on the path of your weekend hike? Take this quiz and find out how much you know about dangerous plants! (Note: While every effort has been made to ensure the accuracy of this quiz, please seek expert advice before handling -- much less eating -- an unfamiliar plant).

Why is it important that some plants have toxins?

Some plants have mechanical defenses against predators, like thorns. But poisonous substances are often a more effective deterrent.


If one part of a plant is toxic, are all its parts toxic?

It's actually very common for plants to have one part that is harmless, and other parts that contain dangerous substances. You'll run across a few examples of those plants in this quiz.


Which of these has toxic leaves, yet is the base for a type of pie?

You might have enjoyed a slice of rhubarb pie -- made from the stalks of the plant -- without knowing that its leaves contain oxalic acid. This acid is hard on the kidneys and dangerous in high doses.


Although a plant contains toxins, it might have medicinal uses.

Surprisingly, it's the dangerous elements of certain plants that make them so useful in pharmacy. Plants that are totally benign are also not biologically active -- in other words, there's a reason no medicine is derived from iceberg lettuce.


What flowering bush with spear-shaped leaves is a poisonous plant well known to Californians and Texans?

Oleander is a durable bush with beautiful flowers in white, pink and magenta. Counties in California and Texas use it as ground cover on roadsides and median strips. Gardeners like it because deer won't eat it. Although it's very common, human fatalities linked to this bush are rare.


Which of these common vegetables has a poisonous berry?

In addition to its poisonous berries, asparagus has another distinction: After consumption, it gives the urine an unpleasant smell. However, not all people can detect it. This seems to be a genetic trait.


The pits of stone fruits often contain a form of which poison?

The pits of cherries, apricots, peaches and several other fruits contain cyanogenic glycoside. When ground up or chewed and ingested, they turn to hydrogen cyanide in the body -- which, in sufficient quantities, can kill.


Which of these plants is part of the genus datura?

'Datura' is the genus that includes about nine species of flowering plants. A close relative of belladonna, datura is dangerous to consume in any of its parts.


Which dangerous plant has a name meaning "beautiful lady"?

"Bella donna" means "beautiful lady" in Italian. She has a bad temper, though -- all parts of the atropa belladonna are poisonous, and can be fatal.


The "atropa" in "atropa belladonna" comes from the name of one of the three Greek _______.

"Atropos" was the oldest of the three Fates in Greek mythology, who cut the thread of a person's life, ending it. This is appropriate given belladonna's deadly nature.


Belladonna is part of a larger family that includes which fruit?

Atropa belladonna is part of the "nightshade" family (Latin name Solanaceae). It includes peppers, potatoes, and tomatoes.


The sumac family of plants includes which bane of hikers?

Sumacs contain an oil called urushiol, which irritates the skin on contact. This is usually an inconvenience, not a true health threat.


Is it dangerous to burn poison ivy in a campfire?

Skin contact usually just causes irritation, as poison ivy is technically an allergen, not a poison (despite the name). But that same allergic reaction inside the lungs can be fatal, so beware of what you're tossing onto a campfire!


If part of a plant is poisonous, is it poisonous at all doses?

Toxicologists like to say "the dose makes the poison." That is, many dangerous substances are not harmful in microdoses. For example, even water causes hyponatremia if you drink gallons of it at a ​time. That said, please don't experiment with small doses -- some plants really are poisonous at low levels!


Which plant, popular around Christmastime, is toxic?

Yes, all of these plants have toxic qualities. So just kiss under the mistletoe -- don't kiss the plant!


Are elderberries safe to eat?

One variety of elderberry, sambucus nigra, is considered safe to eat when cooked fully. Among other varieties, toxicity will depend on the level of ripeness, as well as how thoroughly they are cooked. Proceed with caution, even when getting elderberry products from someone claiming to be an expert herbalist.


Which of these plants contains ricin, a very deadly toxin?

Only a few seeds from the castor bean can kill an adult human. Surprisingly, it still has its uses, most famously as a laxative. (The ricin is rendered biologically inactive by processing).


Oak trees provide which sometimes-edible, sometimes-toxic nut?

The acorn, properly processed, can be a food. But its tannic acid can also sicken the unwary eater.


If a plant is poisonous to one animal, is it poisonous to all?

Differences in the way species evolved means that some animals can easily eat plants that would harm other types. In addition, many plants' main predators are small animals, like birds, and the strength of their toxins evolved accordingly. Because of our greater body mass, humans can often survive eating dangerous plants, although with temporary discomforts like nausea or diarrhea.


The toxin digitalis is found in which plant?

Foxglove is a plant with deep bell-shaped flowers. Fun fact: "Foxglove," along with her lover, Hazel, is one of the most-loved characters from the "Sandman" series by Neil Gaiman.


Digitalis is used as a medicine for which part of the body?

Digitalis makes the heart beat more strongly -- that is, the heart muscle contracts more forcefully. This is dangerous to healthy people, but is helpful in cases of heart failure.


Which allergenic flower is named for an American ambassador to Mexico?

This Christmastime favorite is named for Joel Poinsett, who brought them back to America from Mexico. The poinsettia isn't highly toxic, but getting the sap in your eyes can cause temporary blindness.


Which of these plants contains potentially tumor-causing compounds?

Pyrrolizidine alkaloids -- the substance in question -- are also poisonous to smaller animals, which is probably their main evolutionary purpose. It would be rare for a plant to use a cancer-causing substance as a defense mechanism; cancer works far too slowly to be effective against predators.


Which flowers are the source of the insecticide known as pyrethrin?

Pyrethrins cause serious nerve damage to insects, but have a very low toxicity in humans. For this reason, they are one of the insecticides acceptable in organic agriculture.


Which of these toxic plants also has thorns?

Yep, the holly plant is doubly protected. Small thorns discourage animals from eating the leaves, and a bad case of gastroenteritis will discourage them from consuming much of the red berries.


Which of these toxic plants is commonly a parasite on other trees?

Not only are mistletoe's leaves and berries poisonous, but it grows on trees and leeches nutrients from them. If humans hadn't created a charming Christmas tradition about mistletoe, it would have very little to recommend it!


Which of these natural toxins was promoted (wrongly) as a cancer cure?

From the Greek word "amygdala," meaning "almond," amygdalin is a form of cyanide found in high concentrations in apricot pits. Despite being marketed as "laetrile, the miracle cancer cure," trials have found no therapeutic effect.


Which plant's name sounds like it is warning chickens to stay away?

Henbane has sedative and hallucinogenic properties at low levels, and has been used in religious rituals. Its name isn't a combination of "hen" and "bane," though -- it's probably from the word "bhelena," meaning "death." Cheery!


Which of these toxic plants has a root shaped like a human figure?

Mandrake has strong druglike properties in lower doses, both as a narcotic and a hallucinogen. Because of that, and because of the odd human-like structure of its root, several myths and legends surround the mandrake.


Which of these mushrooms is all the more dangerous because of its resemblance to an edible variety?

The death cap mushroom bears an unlucky resemblance to the straw mushroom. The latter is a tasty addition to Chinese food; the former can cause coma and death. Worse, heating it to common cooking temperatures doesn't destroy the toxin.


Veterinary medicine bonus round: Which of these poses a danger to livestock?

Cattle and horses actually like the taste of locoweed, which is what makes it so dangerous. Many toxic plants are unpalatable, but not "crazyweed."


Veterinary medicine bonus round: Which of these are toxic to cats?

According to PetMD, a variety of plants are toxic to cats, more than the ones listed above. Fortunately, cats have a strong preference for meat and are unlikely to nibble on these plants.


Veterinary medicine bonus round: Is dogbane also dangerous to cats?

Don't let the name fool you. Dogbane, which contains a toxin similar to digitalis, will harm cats too. In fact, despite the fact that we tend to say "cats and dogs" as if they are polar opposites, many plants that are toxic to one species are toxic to the other.


Which of these poisons can NOT be derived from plants?

Arsenic is mineral-derived. On the periodic table, it has the symbol As.


Which plant, used as an herbal antidepressant, causes a number of adverse drug interactions?

St. John's Wort was a popular alternative to pharmaceutical antidepressants in the late 20th century. Enthusiasm waned somewhat when it became clear how often it interfered with the action of other drugs, such as contraceptives and immunosuppressant medications.


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