It carries a parasite of Monarch Butterflies known as Ophryocystis elektroscirrha, or OE, which may cause defects in the wings of Monarchs. As it doesn’t die back again and can bloom late, the plant alone may also confuse Monarchs by signaling a breeding year when it’s time emigrate. This article https://swamp-milkweed-annual-or19753.blogsvila.com/31050905/detailed-notes-on-are-milkweed-plants-annual-or-perennial