Butterfly Milkweed - Asclepias tuberosa

Asclepias species have been in the news off and on for the last couple decades due to them being host plants for Danaus plexippus (Monarch butterfly) whose decline, along with Apis mellifera (European honey bee), has led the way in bringing insect conservation to public attention. Asclepias species are specific host plants for D. plexippus who rely on Asclepias for every life stage except adulthood. Adults lay their eggs on an A. speciosa plant, when the eggs hatch the caterpillars consume the leaves of A. speciosa, absorbing the cardenolides produced by the plant. Cardenolides are steroid toxins that effect the heart of most mammals and make D. plexippus caterpillars taste foul to predators. The caterpillars form their chrysalis on an A. speciosa individual where they remain until they emerge as an adult butterfly. However, A. speciosa is important to more wildlife than just D. plexippus. A. speciosa offers a large quantity of nectar in exchange for pollination by bees, butterflies, wasps and hummingbirds, making it an important and preferred food source for these various pollinators.

Narrowleaf or Mexican whorled milkweed (Asclepias fascicularis) in my neighborhood. This is easily our most abundant local milkweed. The monarch butterfly’s larval food source and a critical habitat plant. I’ll probably guerilla plant these all over this fall

Use the Milkweed Seed Finder from Xerces Society

Infographic: onEarth, National Resources Defense Council