Consisting of over 2000 species from Africa, Madagascar, and the Americas, Euphorbia is one of the most diverse genus of plants. They range from annual or perennial herbs, to woody shrubs, to trees, and many are succulent.  They have a milky-white sap which is poisonous, and should be handled with care.  Use gloves when handling, and immediately wash off any sap that comes into contact with the skin.