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Map credit: USDA, NRCS. 2014.



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Asclepias syriaca, common milkweed


Description: Common milkweed is a perennial herbaceous plant growing 1.9 to 6.5 feet tall. Its small, green to purple flowers have both male and female parts. Flowers are grouped into showy clusters.


Habitats: Common milkweed is found along banks and flood plains of lakes, ponds, and waterways, and in prairies, forest margins, roadsides, and waste places.


Phenology highlights: Common milkweed is used by many insects including butterflies and bees, and the alert observer may see pollinators, eggs, or caterpillars on milkweed. 


Species facts: 

•Milkweed pollinators include monarchs, other butterflies, bees, and other beneficial insects.

•Milkweed is required for monarch reproduction. The female butterfly must lay her eggs on milkweed since that is the only food the caterpillars can eat.

•Compounds in milkweed sap make the flesh of caterpillars feeding on the plants distasteful to most predators.

•People have used milkweed for fiber, food, and medicine across the U. S. and southern Canada. 



Why observe this species? Common milkweed has been selected for monitoring by a Nature’s Notebook partner, Monarch Watch, because monarch butterflies require milkweeds for their survival. Monarch populations have declined over 90% since the 1990’s.


Tip for observing this species: For common milkweed, be sure to wait until the fruits split open to expose the seeds before recording ‘yes’ for the “ripe fruits” phenophase.






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