Due to the presence of sensitive species and difficult access, visitation at the Walnut Hill preserve is restricted. This preserve supports a high quality occurrence of smooth purple coneflower, known from only 15 sites in the world. The coneflower is federally listed as an endangered species.
Walnut Hill is a gently sloping old field with abundant grasses and sedges, interspersed with red cedar, redbud, locust and walnut. More than 1,000 smooth purple coneflowers exist here. This species, a member of the daisy family, is a tall perennial that flowers in June and July. Stiffly erect and generally unbranched, it may reach a height of five feet. The coneflower forms a cone-like head, ringed by drooping ray florets. It is closely related to the common purple coneflower that is one of the sources of the medicinal herb Echinacea, but in addition to being smoother, it has longer and narrower corolla rays.
Ellison and Mary Linda Smyth donated Walnut Hill to The Nature Conservancy. Mrs. Smyth, a botanist, had realized that the tall purple perennial blooming in their field was unusual. Through her job at the Virginia Tech herbarium, she located the plant in The Nature Conservancy's computerized inventory of rare species. She discovered that her land contained the largest documented population of smooth purple coneflowers in the world. Realizing that The Nature Conservancy could provide these plants with the necessary long-term stewardship, the Smyths chose to turn the land over to the Conservancy's Virginia chapter.
At Walnut Hill, the coneflowers are growing in a successional field of broom sedge (or bluestem) which is slowly yielding to forest. The population is threatened by land use changes, particularly livestock grazing. However, the greatest threat to their survival is the shade that results from the invasion of woody species. The Conservancy now monitors the plants and manages the habitat to keep the coneflower population healthy.