Favoritos de mertensia

Came back to take better photos of this plant. It is only this plant in this spot, I didn't see a colony. The leaves are rough. I checked Floraquest for the northeast to help with ID and this plant resembles this species. Normally found further south it seems.

I found several populations of this Baccharis that is not identifiable- it’s not any of our FL native species.
All plants across the region are less than 2ft tall, and have fleshy leaves. Occurring in coastal salt marsh, co-occurring with B. angustifolius, B. glomeruliflora, and B. halimifolia - all of which exhibit their typical height and characteristics.
Not sure if this is undescribed, or a species not know to occur in FL which isn’t representatives in our floristic keys.

Photos 2-4 are comparison of P. susquehanae (left) with Aronia melanocarpa (right), with which it frequently intermingles and superficially resembles from afar. Note the presence of glands, absence of black dots on the midvein, and red petiole on the Prunus. The Prunus also tends to have whiter undersides (see third photo).