7 Of The Most Poisonous Plants In The World

I’m sure you already know that there are many poisonous plants on Earth, but some are more poisonous than others.

I’m sure you already know that there are many poisonous plants on Earth, but some are more poisonous than others.  I think you’ll be surprised by some of the plants on this list.

Water Hemlock 

Water Hemlock is a relative of Poison Hemlock, the plant that the famous philosopher, Socrates, was made to drink after being convicted of heresy.  Water Hemlock is a tricky one to pick out since it so closely resembles Queen Anne’s Lace, Carrots and Parsnips.  The killer in this plant’s case is cicutoxin, which can be found throughout the plant but is concentrated in the roots.  Upon ingestion, symptoms such as cramps, nausea and convulsions occur.  People who have survived ingestion usually have lasting symptoms like amnesia and tremors.

White Snakeroot

White Snakeroot is an herb that grows in North America.  It has leaves that resemble those of the strawberry plant, and produces clusters of white flowers.  It contains the poison, trematol, which is a toxic alcohol.  People are usually poisoned by this plant after ingesting milk or meat from livestock that have eaten the plant.  Abraham Lincoln’s mother-in-law died as a result of drinking cow’s milk from a cow that had eaten White Snakeroot.  Symptoms of ingestion are cramps, nausea, weakness, red tongue and high blood acidity.

Castor Bean

Even though this is the plant that is used to make Castor Oil, it should never be consumed without being correctly processed.  The beans of this plant contain the deadly toxin, Ricin, and just 8 seeds are enough to kill an adult.  The plant is native to Africa, but can be found in North America where it is grown as an ornamental plant.  Symptoms of ricin poisoning are nausea, vomiting, diarrhea, and seizures.  In recent years, ricin has been sent through the mail to politicians in the U.S. in failed assassination attempts.  Most deaths occur in children and pets who accidentally ingest the beans.  It only takes 2 beans to kill a child.


Wisteria is one of my very favorite flowers and I was surprised that it is so poisonous.  Wisteria are vining plants that can grow quite large and as tall as 60 ft.  They originated from Japan but can now be found in all parts of the world.  The entire plant is poisonous and, if ingested, can cause nausea, vomiting, diarrhea, and high fever.


Oleander is a popular ornamental plant in hot, dry areas.  It can be found all over Southern California where it is prized for its drought tolerance and beautiful flowers.  But, it can be deadly if any part of the plant is ingested.  It contains the toxins oleandrin and neriine which can cause lethal cardiac symptoms.  Ingestion can cause erratic heartbeat, nausea, vomiting, diarrhea, seizures and coma.  People have even fallen ill after eating honey from bees that obtained pollen from Oleander flowers.

European Yew

The European Yew is one of the oldest trees in Europe.  It’s a very slow-growing plant that can reach a height of 132 feet tall at maturity.  All parts of the plant are toxic except for the aril – the fleshy red covering around the seed.  The plant contains the toxin, taxin(e), which is rapidly absorbed in the body.  The plant is more toxic when dried.  Symptoms of ingestion include nausea, diarrhea, heart and lung problems, tremors, convulsions and irregular heartbeat.


If you’ve ever wondered why smoking is so bad for you, here is your answer.  Tobacco contains nicotine and anabasine, two alkaloid toxins that can be deadly if ingested.  Tobacco is perhaps the most widely consumed toxic substance in the world.  It is both psychoactive and extremely addictive.  Tobacco actually is designated as a heart toxin, yet it continues to be widely manufactured and consumed.  Over 5 million deaths per year are a direct result of Tobacco use, which makes it the most lethal plant in the world.

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