Standing under a Manchineel tree during rain can cause your skin to blister.

The Manchineel tree grows in tropical areas like Florida and the Caribbean. It contains a chemical called phorbol. This substance dissolves easily in water. When rain hits the leaves, it carries the phorbol down onto anyone standing below.Every part of the tree is dangerous. The fruit looks like a small green apple but causes the throat to swell shut if eaten. In 2000, a doctor named Nicola Strickland wrote about the intense pain she felt after eating just one tiny piece. She described a burning feeling that lasted for hours.The tree is also dangerous if it is damaged. Cutting the wood sprays toxic sap into the air. Burning the wood creates smoke that can cause permanent blindness or lung damage. Because of these risks, many trees are marked with red paint or warning signs to keep people away.