is known as the dogbane family, and its members are found all across the US, in a wide variety of environments. Most common of the 45 US genera (215 species) is asclepias, the milkweeds. Apocynaceae plants may be herbs, vines or woody shrubs, producing flowers singly or (more commonly) in clusters, usually spherical. Individual flowers consist of five sepals, five sepals and five stamens. The filament column is often attached to five appendages, variable in shape and color. Leaves are undivided, usually opposite or whorled. Many species have milky sap.