Asclepias verticillata ( Whorled Milkweed or Horsetail Milkweed ) is a particular kind of milkweed used as a medicinal plant . Asclepias verticillata ( Whorled Milkweed , or Horsetail Milkweed ) is a species of milkweed which is used as a medicinal plant by Native American tribes and in Butterfly gardening .