Asclepias (Milkweed)

Host plant for the monarch butterfly, critical to their survival

The genus Asclepias contains perennial wildflowers, commonly called milkweeds for the milky sap that oozes from their stems and leaves when cut. Milkweeds are an important host plant and food source for butterflies. In fact, they are the only food source for monarch butterfly larvae (caterpillars) and are vital to their survival. However, milkweeds sustain many pollinators, including bees and beneficial insects.

Considered to be some of the showiest native wildflowers, milkweeds usually bloom spring through summer and set long-lasting clusters of small, five-petaled flowers borne on erect or drooping stalks. Nectar rich, the flowers are white, yellow, green, purple, pink, orange, or red, depending on variety. In fall, their podlike fruits split open and disperse hundreds of, usually, tufted, silky-haired seeds by wind. The attractive seed pods and the flowers are both used in floral displays.

Asclepias is a genus of about 140 species that occur in a wide range of natural habitats in North and South America. Most milkweeds are deciduous, but a few are evergreen. The plants vary in stature: some are tall and stout; some are low-growing and sprawling; and some are multi-stemmed and clumping. All milkweeds self-seed, but some species are also rhizomatous and can grow into dense stands and form extensive colonies in the wild.

A number of Asclepias species are grown horticulturally. But, to provide the greatest benefit to butterflies, grow species that are regionally appropriate or native to your area. The following 3 species are cold hardy and can be grown almost anywhere: A. incarnata (swamp milkweed), A. syriaca (common milkweed), and A. tuberosa (butterfly weed), which has less sap than most milkweeds.