poisonous-plantsPlants are an important part of nature. They are everywhere in the world and makes our planet green. We all know that they are good for us because they provide us food, wood, and the precious oxygen. But, there are many species of plants that also carry poisons. These poisons may cause itching, vomiting, diarrhea, and even death. The poisonous plants play an important role in nature. Let’s dig in deep!

Why Plants Carry Poison?

The first question that everyone will probably ask about the poisonous plants is that, why plants carry poison with them? Because we know plants as good creatures that provide a primary food source to animals, so why they will want to harm the animals? There are some reasons behind it, let’s discuss them.

The primary reason to carry the poison is the protection from herbivores. Herbivores (plant eaters) consume the plants to survive. Suppose if some herbivores start to eat one plant together, they may consume the whole plants. As a result, the plant will die completely. So, some plants have evolved to carry poison in them with varying amount of poison to protect them against herbivory when they are consumed more than average.

Some plants carry permanent poison to protect themselves from herbivores. For examples, leaves of mangrove tree are poisonous to many herbivores. But, few herbivores are able to digest these poisonous leaves, e.g. sloths. As a result, few species can eat these leaves which helps mangrove to survive while providing food to limited herbivores.

Sloth is hanging on a mangrove tree

Uses of Poisonous Plants

Poisons of the plants are of course harmful to animals and humans. But, they are also used by humans in the preparation of some medicines and in some other applications. For example, people have used the poison of ‘Buckeye’ for catching fishes. ‘Digitalis’ plant has provided the first remedy for cardiac, which helped in strengthening the heartbeat.

The Most Poisonous Plants on Earth

Here are some of the plants that are considered most poisonous in the world.

1. Aconitum napellus

It is a beautiful plant with purple color. When eaten it may cause numbness, vomiting and also death. In 2014, BBC reported that a 33 years old gardener died due to touching (or eating) this plant.

2. Castor Bean

When this plant is eaten, it may cause vomiting, bloody diarrhea, increased heart rate, low blood pressure, and death in few days (if the victim is not treated well).

3. Water Hemlock

It is also a beautiful plant with small white-colored flowers. This plant may cause seizures if eaten. It is also the common poisonous plant in UK and US.

Fun Facts

  • Leaves of the apple tree and its seeds contain ‘cyanide’; a very poisonous chemical.
  • Unripen potatoes are also poisonous. They may cause vomiting.
  • Some poisonous plants can cause very intense itching when touched, e.g. Poison Ivy.


Cite this Page

Abdul Wahab, "Poisonous Plants," in Science4Fun, June 19, 2022, https://science4fun.info/poisonous-plants/.