Jane and Glenn have mostly this milkweed, it is called Tropical Milk-Weed.  It originated in South America. I have the common one that is native to the northern hemisphere. The tropical one drew ten times or more monarch eggs than the common ones at our place did this year. It was rather quiet here but a menagerie over there. Thirty or so monarchs laid their eggs, became larvae, pupated, entered chrysalis and then emerged as adult marvelous monarch butterflies and they are still at it. This is all part of their amazing life story that includes the winter in Mexico.