It is always best to select a Asclepias species that is a native plant in your region, as these are always well-suited to native butterfly populations. There are many such plant species that are native to North America, including:  Asclepias speciosa (showy milkweed) is found in much of Western North America. It is hardy in zones 3 to 9. Asclepias verticillata (whorled milkweed) is found throughout the U.S. and is hardy in zones 4 to 9. Though not especially showy, it is a monarch butterfly magnet. Asclepias purpurascens (purple milkweed) is a pretty, though weedy, species native to eastern North America. It is hardy in zones 3 to 8. Asclepias tuberosa (butterfly weed) is a very popular garden plant with orange to yellow flowers. Many cultivars are available. It is hardy in zones 4 to 9. Asclepias incarnata (swamp milkweed) is a white-flowered species native to damp, boggy areas of the central U.S. It is hardy in zones 3 to 9; several cultivars are available.