Cheilanthes feei New to Virginia

Abstract

The Slender Lip Fern, Cheilanthes feei Moore, is a widely distributed species of the western United States which occurs eastward to Arkansas, Missouri, Kentucky, and Illinois (Fernald, 1950; Steyermark, 1963; Cranfill, 1980; Mohlenbrock, 1967). The easternmost station for this fern was along Cedar Creek in Bullitt County, Kentucky, in a region known as The Knobs. This small population, discovered originally by Clyde Reed (Reed, 1952), is thought to be disjunct from the next nearest stations along the Ohio River in southern Illinois (Cranfill, 1980). Cheilanthes feei was discovered in 1979 by Bentley during a routine survey of the plants of Claytor Lake State Park, Pulaski County, Virginia. The actual identity of the plant went unknown until the station was visited by the authors on May 8, 1981, when the first voucher collections were made. This discovery is a remarkable disjunction of approximately 450 km eastward from the Bullitt County, Kentucky station and nearly 650 km from the more contiguous portion of its range from Illinois westward. The preferred habitats of this fern are dry, exposed crevices in limestone or dolomite cliffs (Wherry, 1961; Mohlenbrock, 1967). Extensive exposures of this kind may be found along the New River in Virginia. Claytor Lake is a large impoundment of some 4500 acres formed in 1939 when the Appalachian Power Company built its Claytor Dam on the New River just upstream of Radford, Montgomery County, Virginia. In the southeastern sector of Pulaski County, the New River is deeply entrenched where it has cut through thick beds of limestone of the Rome formation and Elbrook dolomite, both of Cambrian origin. The more resistant dolomite forms nearly vertical cliffs, frequently several hundred feet high. The station for C. feei is a rather small but precipitous cliff, perhaps fifty feet high, which forms a nose-like projection along a westward facing portion of the shoreline. Because of the configuration of the rock, the exposures range from northwestern to southern. During a second visit to the outcrop on May 14, 1981, an estimate of 1200 plants was made. Most of these are extremely small and occupy nearly every minute fracture in the rock. Several hundred larger, mature plants crowd the deeper cracks and more protected, overhanging sites. Several smaller, shaded outcrops in oak woods adjacent to the main cliff support a considerable number of additional plants. Adjacent areas of the lake shore, where similar outcrops and exposures occur, were searched for additional populations of C. feei, but only six other plants were found on a very small ledge at the water level several hundred feet to the north. Since the normal pool elevation is approximately eighty-feet above the former river level, this same outcrop was undoubtedly much more extensive prior to flooding. A much larger population may have existed and, of course, other nearby populations may have been inundated by the lake waters.