The flowering plants are considered among the most poisonous trees in the world and are native to Florida, the Bahamas, the Caribbean, Central America and northern South America. The Spanish name is "manzanilla de la muerte: which means "little apple of death."
In fact, it's not just the fruit (which does in fact resemble little apples) that is poisonous, but the entire tree is toxic to humans and animals. The tree oozes a white sap when it rains, so standing beneath the tree can cause blistering of the skin. Burning the tree releases extremely toxic fumes which can cause blindness and respiratory problems when humans come into contact with the smoke. Consumption is generally fatal, and it's, by all accounts, an agonizing death.
It is common for locals to mark the tree with signs or a red X on the trunk to keep people away. The sign on the tree above reads: "Warning! The leaves, bark, and fruits of these trees contain a caustic sap which may be injurious if touched. Columbus described the small green fruits as 'death apples.' The trees are common along the Caribbean shores. Avoid contact with any part of this tree!"

3. Deadly Nightshade (Atropa Belladonna)

Castor oil has long been used to aid digestion. While it has a foul taste and consistency, it is not harmful when ingested, yet you may be surprised to learn that just one bean from the plant that is used to make castor oil can be fatal to an adult in minutes.
That's because when they make castor oil they remove a lethal compound called ricin, making the oil safe to consume. While usually fatal, if consumption of the castor bean doesn't kill you, you can look forward to symptoms like nausea, emesis, diarrhea, tachycardia, hypotension and seizures, often persisting for up to a week.

5. Water Hemlock (Cicuta)