MONARCH BUTTERFLY FOOD

This is Common Milkweed (Asclepias syriaca); the only known food for the caterpillar of the Monarch Butterfly (Danaus plexxipus).
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This plant's milky sap (hence the name) contains cardiac glycosides; in fact, all parts of the plant are toxic and, if ingested, can cause cardiac rhythm changes and a severe drop in bpm.  The plant is most toxic just before maturity.
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The larvae (caterpillars) of this butterfly are immune to the toxin and, indeed, become toxic themselves after ingesting it.  Any predator eating one quickly learns to avoid them.  Some other butterflies (e.g. the Viceroy) mimic the color of the Monarch and this mimicry affords them some measure of protection against predation despite the fact that they are not toxic....it's a commensalistic relationship known as Batesian mimicry. (I have no idea who Bates is/was....likely the first individual to name the relationship).
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Learn here about Monarch Butterflies:  https://www.wildcenter.org/our-work/all-about-monarchs/?gad_source=1&gad_campaignid=22451491911&gbraid=0AAAAADvIAAimYNvY7cch3aNEXEmaKWHBK&gclid=EAIaIQobChMI2_as6_2rjgMVgHJ_AB053zPhEAAYASAAEgIEffD_BwE
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BEST IN LARGE
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EXTRA:  Added ex post facto in response to Skyegirl's comment.  Monarch caterpillar feeding on milkweed. The striped colors are a cryptic warning to predators....."Eat at your own risk."  I'm pretty sure I've blipped this image a while back...several years ago.  OK to Blip it again?