This Malachite Butterfly has its proboscis deep in the Snakeroot flower probing for nectar.

I looked up this plant after I found Malachite Butterflies feasting all over it. My best guess is that it is Hammock Snakeroot, Ageratina jucunda. It grows about 5 feet tall (and I've found some much taller now) on the edges of wooded areas. In the photo below, a Julia Butterfly nectars on Hammock Snakeroot:

I brought some seeds home, but they didn't make it. I'll try again when our drought ends. I really want this nectar plant in my yard!

Left - Monarch Butterfly, Above - Zebra Heliconian Butterfly, Below left - Giant Swallowtail Butterfly Below right -Ruddy Daggerwing Butterfly

All of these butterflies were sipping nectar from the same patch of Hammock Snakeroot Flowers at the same time. It is an excellent fall/winter nectar source.

The Snakeroot flowers are white with a hint of a purple-pink color depending on which way the light hits them. They're small and wispy, but pretty in a very natural sort of way, particularly when they're covered in a cloud of butterflies.