Mead's Milkweed, Asclepias meadii, is rare in Missouri and even rarer in Illinois and southern Iowa. It is a federally listed threatened species.
According to "Tallgrass Prairie Wildflowers": "Mead's Milkweeds can only produce seeds when pollen from one plant reaches a different individual. Recent research suggests that some populations of Mead's Milkweed may be genetically identical, and thus incapable of pollination within the group."
