Manchineel
This is widely considered as the most poisonous tree in the world and with good reason. Found in the coastal regions of Florida and South/Central America, the whole of this tree can cause you severe problems. The fruit is known as ‘little apples of death’ as eating one can kill you due to the toxins found within it. However, this is probably not the main issue we face with this tree.
The bark and sap are stuffed full of powerful irritants like phorbol that causes skin to blister painfully if exposed to it. In effect, it is a kind of allergic dermatitis and obviously to be avoided at all costs. It is thought so potent it could strip paint off a car. So you really don’t want that on your skin! One key point to note is that this can happen from rain falling off the leaves onto exposed skin. Don’t make the mistake of sheltering under this tree in a storm!