Like many wildflowers, this plant goes by several names, including Black-eyed Susan. But Orange Coneflower, or R. fulgida, differs from Black-eyed Susan (R. hirta) in a a couple of ways, even though the flower heads can be very similar in appearance.
The primary difference seems to be the leaves and stems. Black-eyed Susan, or Rudbeckia hirta, is a bristly-hairy species with lance-shaped leaves. Small white hairs completely cover the stems, leaves, and bracts. By contrast, Orange Coneflower, or Rudbeckia fulgida, has stems and leaves that are sparsely haired, and the leaves are medium to dark green, ovate to oblong to oblanceolate, and can be toothed or entire.
The flowers generally occur one per stem. The heads have 10 to 15 ray flowers that are are yellow; the base of each petal near the base can be darker yellow to orange. The central disk is dark brown and domed.
Orange coneflower is a perennial, while Black-eyed Susan is a self-seeding annual or biennial. It prefers dry, prarie-like conditions and require little care in the home garden (drought tolerant). There are many varieties of R. fulgida that are grown as garden ornamentals, so the be aware that the foliage can vary quite a bit from place to place. One website calls them “a source of taxonomic problems that continue to this day”, and i couldn’t agree more!
Compare the leaves of R. hirta and R. fulgida: