Plant of the Week: Showy Milkweed

A monarch butterfly on showy milkweed. Image Courtesy of US Fish and Wildlife. Image Source: https://www.fws.gov/pacific/images/feature/2017/highlights/Milkweed.jpg

Now that our lab group is working on native plants and native bees, I thought it would be fun to do a ‘Plant of the Week’ and ‘Bee of the Week’ series.  This second entry is from Lucas Costner, an undergraduate environmental science major at Oregon State University.  It highlights one of the plants that Aaron Anderson is using in his research.

The showy milkweed (Asclepias speciosa) is a perennial forb, native to the western United States and Canada(3).  It is hardy through USDA zones 3a to 9b (1). While the showy milkweed is listed as threatened in Iowa, it can become fairly weedy once introduced to gardens if left unmanaged, due to rhizomatous growth

(3). The plants do best in full-sun, and are an excellent choice for gardeners looking for a low-maintenance, native plant that is very attractive to pollinators (3). In particular, the showy milkweed is known for its attractiveness to the monarch butterfly (Danaus plexippus), which utilizes the plant for habitat, as well as a larval host plant and adult nectar source (1,2,3). The monarch butterfly is not alone in its use of the showy milkweed.  Eleven other species of Lepidoptera are known to reproduce on milkweeds (2), and the flowers are frequented by many species of bees and hummingbirds (1). The flowers are an appealing addition to the garden from an aesthetic perspective as well, featuring large, dense umbels of pink star-shaped flowers from May through September (3). The stems can reach heights of up to five feet and

have oppositely spaced, elongate leaves that are gray-green in color and covered in small hairs (3). At the end of the season, the flowers form interestingly shaped fruit pods packed with seeds whose silky white hairs are specially adapted for wind dispersal.

1. ”Showy Milkweed for Western Monarchs.” Monarch Butterfly Garden. N.p., n.d. Web. 26 June 2017. <http://monarchbutterflygarden.net/milkweed-plant-seed-resources/asclepias-speciosa/>.

2. Tallamy, Douglas W. Bringing Nature Home: How You Can Sustain Wildlife with Native Plants. Portland: Timber Press, 2009. Print.

3. Young-Mathews, Annie, and Eric Eldregde. Plant fact sheet for showy milkweed (Asclepias speciosa). Corvallis: USDA- Natural Resources Conservation Service, Aug. 2012. PDF.