Summary ⁶

Asclepias syriaca, commonly called common milkweed, butterfly flower, silkweed, silky swallow-wort, and Virginia silkweed, is a species of flowering plant. It is in the genus Asclepias, the milkweeds. It is native to southern Canada and much of the United States east of the Rocky Mountains, excluding the drier parts of the prairies. It grows in sandy soils as well as other kinds of soils in sunny areas.

Ecology ⁷

More than 450 insects species feed on Asclepias syriaca, including flies, beetles, ants, bees, wasps, and butterflies; it is an important food source for monarch butterfly caterpillars (Danaus plexippus); other species that feed on the plant include red milkweed beetle (Tetraopes tetraophthalmus), the milkweed tussock caterpillar (Euchaetes egle) and Oncopeltus fasciatus and Lygaeus kalmia. Many kinds of insects visit A. syriaca flowers, and some kinds pollinate them, including Apis mellifera, the Western honey bee, and native Bombus spp. (bumblebees).

Monarch butterfly larvae consume only milkweeds, and monarch populations may decline when milkweeds are eliminated with herbicides. The development and widely adopted cultivation of herbicide-resistant staple crops such as corn and soybeans have led to a massive reduction in weeds and native plants such as milkweeds. Subsequently, this has played a significant part in the population decline of the monarch butterfly. In 2018 the CEO of the National Wildlife Federation stated that the population of the monarch butterfly is now down 90 percent in the last 20 years and cited the reduction in milkweed as a contributing factor.

Many parts of the United States face a reduction in milkweed population due to factors such as increased habitat loss due to development, roadside median mowing, and herbicide use.^{[citation needed]} Despite this, deforestation due to human settlement may have expanded the range and density of common milkweed in some regions. Milkweed has even become invasive as it is naturalized in several areas outside of its original native range, including Oregon and some parts of Europe.^{[citation needed]}

Read More ⁸

• https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=b480
• https://www.illinoiswildflowers.info/weeds/plants/cm_milkweed.htm
• https://www.wildflower.org/plants/result.php?id_plant=ASSY

Sources and Credits

1. (c) Jozefsu, some rights reserved (CC BY-SA), http://commons.wikimedia.org/wiki/File:Asclepias_syriaca_%2B_Pieris_rapae.jpg
2. (c) Meneerke bloem, some rights reserved (CC BY-SA), http://commons.wikimedia.org/wiki/File:Asclepias_syriaca03.jpg
3. (c) Sandy Wolkenberg, some rights reserved (CC BY), uploaded by Sandy Wolkenberg
4. (c) Liv MW, some rights reserved (CC BY-NC-SA), uploaded by Liv MW
5. (c) John Beetham, some rights reserved (CC BY-NC), uploaded by John Beetham
6. (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Asclepias_syriaca
7. Adapted by Murfreesboro,TN, Natural Resource Division from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Asclepias_syriaca
8. (c) Lauren LeCroy May, some rights reserved (CC BY-SA)

More Info

• iNat taxon page
• African Plants - a photo guide
• Biodiversity Heritage Library
• BOLD Systems BIN search
• eFloras.org
• Flora of North America (beta)
• Global Biodiversity Information Facility (GBIF)
• Go Botany
• HOSTS - a Database of the World's Lepidopteran Hostplants
• IPNI (with links to POWO, WFO, and BHL)
• Maryland Biodiversity Project
• NatureServe Explorer 2.0
• SEINet Symbiota portals
• Tropicos
• USDA PLANTS database
• VASCAN by Canadensys
• World Flora Online
• 日本のレッドデータ検索システム
• 植物和名−学名インデックス YList

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