Rudbeckia? Coreopsis? (Jasper Co. Tall Yellow Coneflower)

Description

This 6′-8′ tall evergreen tight clumping  native perennial bloom repeatedly from July through January (at least some years) drawing clouds of bees and butterflies. Birds feed on the seeds. A well behaved plant forms tight clumps over several years. Although very tall, does not flop.  Plant in sun or shade in average to wet soil. I have never seen deer browse this plant, even in the garden where they destroyed the basil. It Very rare locally. We propagated our plants from a native population on a steep ravine in Jasper County, SC. I have never seen it growing wild anywhere else In the past, I sold it as “Coreopsis tripteris” but it has been suggested that it is a Rudbeckia. I hope to determine its true identity.