Showy Milkweed (Asclepias speciosa) is the host plant of the monarch butterfly and an important nectar source for bees and butterflies. Native to the western portion of Canada and the United States, this species spreads less aggressively than it's cousin Common Milkweed. The blooms are incredibly fragrant. Common milkweed sap is toxic, so growing it in areas where livestock graze should be discouraged. An alternative are non-toxic swamp or butterfly milkweed.