Gravel Root; Post from 7song on FB for Reference :D

Thank you 7song!

Eupatorium (Eutrochium) maculatum is the photo feature for tonight. Joe pye weed and Gravel root are two of its common names. It is a stately plant, often growing in the proximity of its cousin Eupatorium perfoliatum (Boneset), near water.
This plant is often confused with Eupatorium purpureum (still to come), but there are a few notable differences.
One is that Eupatorium purpureum tends to grow in drier places than E. maculatum. The second is that Eupatorium maculatum has about 8-20 florets per individual involucral head, and Eupatorium purpureum has approximately 4-10. While this may seem confusing for now, there will be more details of this detail later. The question remains; that while they are used interchangeably, might there be difference between these two Gravel roots as medicine?