Killer Seeds

Along the banks of an African river, spiky reddish flowers hold shiny, purplish‑brown seeds. A gentle wind blows the ripe seeds. Some of them tumble to the ground. A hungry bird wanders by. Though the castor bean seeds sparkle, the bird passes them. It knows these seeds can kill.


Castor beans are the deadly part of the world’s most poisonous plant.

Castor bean plants came from tropical Africa. But, they now are grown in gardens around the world. The plant is exotic and beautiful for gardens. Yet, the castor bean plant holds the record for the world’s most poisonous plant.

Within these seeds is a deadly poison called ricin. A small handful of seeds can kill a person. But, the plant needs this poison. It protects the seeds from being eaten. For safe handling by humans, the seeds must be heated to neutralize the poison.

The Sting Is the Thing

It’s morning in a tropical rain forest in Australia. Sunlight sparkles across a growth of heart‑shaped leaves. Each leaf of the gympie‑gympie tree is coated with shimmering fuzz. It’s beautiful, but watch out!

The fuzz is made up of hollow, needle‑like hairs. Each is filled with a painful poison. You only need to touch the plant to get stung. The hairs enter your skin and break off. As your skin closes over them, it traps the hairs.

Native animals, like the green possum, eat the leaves with no effect. Humans, horses, and dogs, however, can experience a crippling pain after a simple brush against the plant. The plant can’t survive without these needle‑like hairs, however. They do a lot to protect the plant from being disturbed by large animals.


The hair‑like needles of the gympie‑gympie carry a painful toxin.