It carries a parasite of Monarch Butterflies called Ophryocystis elektroscirrha, or OE, which often can result in defects during the wings of Monarchs. Because it doesn’t die back and might bloom late, the plant by itself may also confuse Monarchs by signaling a breeding year when it’s time to migrate. https://aremilkweedplantsperennia33322.blogdosaga.com/30846442/considerations-to-know-about-is-swamp-milkweed-a-perennial