This is Asclepias sullivantii, also known as Prairie Milkweed. This wonderful asclepias is similar to common milkweed, but it is less aggressive and works great in a garden. This milkweed is listed as threatened in Michigan, Minnesota, and Wisconsin, so this would be a great butterfly garden plant for any of those states. Asclepias in general are documented nectar sources for the Monarch, Orange-edged Roadside-Skipper, Dina Yellow, Carus Skipper, Eastern Tiger Swallowtail, and Falcate Metalmark butterflies. It is also the nectar source for the Clarks sphinx, and Milkweed Tussock moths. USDA Hardiness Zones 4 to 9