Sandbox Tree (aka Dynamite Tree)
The Sandbox Tree (Hura Crepitans) grows primarily in South America, the Amazon rain-forest and certain parts of North America.
This tree is completely dangerous. The pumpkin shaped fruit it grows causes (upon consumption) vomiting, diarrhea and cramps. The sap from the tree is toxic and was once used to poison the tips of darts for combat. It can also cause blindness if it comes into contact with the eye.
The really cool (and also dangerous) thing about this tree is how the fruits explode. When they’re ripe, the hardened seed capsules explode and send flat, hard seeds over a 60 feet radius at 150 MPH (~240 KPH).