Enchanted Rock State Natural Area
Enchanted Rock State Natural Area is a 1,643 acre property owned by the state of Texas and managed for wildlife and tourism. The land was purchased from private landowner Charles Moss by the Nature Conservancy of Texas in 1978 and was later sold to the state of Texas. The park opened as a state natural area in 1978. Prior to its acquisition by the Nature Conservancy, the property was held by several private landowners and used for cattle ranching and tourism.
Within the park boundary sits Enchanted Rock, a large granite dome for which the park is named. Reaching a height of 137 m above the surrounding landscape, this is the highest point on the property. Enchanted Rock spans the border of southern Llano and northern Gillespie counties in the Llano Uplift of central Texas. This primarily granite region includes the majority of Llano and Mason counties, but extends into 8 additional bordering counties and covers approximately 5,180 km2 on the eastern margin of the Edwards Plateau.
Flora of Enchanted Rock
This popular natural area supports a wide diversity of plants and animals and is one of the few remaining natural spaces in the region. The goal of this project is to document, photograph, and collect herbarium voucher specimens for all of the plant species that grow at Enchanted Rock State Natural Area. Research Associate Bob O’Kennon has worked at Enchanted Rock for approximately 30 years, collecting and documenting the plants that grow there. Starting in 2014, BRIT researcher Kim Taylor joined Bob in an effort to complete the project.
All plant species encountered within the park were documented and collected as herbarium specimens. These specimens were identified, labeled, glued to high quality paper, and filed into the herbarium. They provide the evidence that a plant was growing in a specific location at a specific time. Many of the specimens collected can be viewed on BRIT’s online digital herbarium. Bob and Kim have documented 948 species from Enchanted Rock. They have submitted their work for publication in the Journal of the Botanical Research Institute of Texas to be published in the spring of 2016.
Cyperus granitophilus (granite flat sedge) Discovered in Texas
During the course of the flora of Enchanted Rock project, several interesting species were found. One species of note is Cyperus granitophilus (granite flat sedge). This species is a member of the sedge family (Cyperaceae) that is known to occur in the Piedmont granite regions of Georgia, Alabama, South Carolina, North Carolina, and Virginia. This species only grows on granite outcrops. While conducting field work for the flora of Enchanted Rock, Bob O’Kennon and Kim Taylor discovered a sedge that they did not recognize. They collected the plant and later identified it as Cyperus granitophilus. This represented the first time this plant had knowingly been collected in the state of Texas, some 790 miles from its known range in the Southeastern United States.
After discovering the species, Bob and Kim set out to determine its true distribution. In order to do this, they examined herbarium specimens of a closely related species, Cyperus squarrosus. This species looks very similar to C. granitophilus. They examined herbarium specimens from the BRIT herbarium, the University of Texas, Texas A & M University, and the University of Oklahoma, and discovered that several of the specimens were actually Cyperus granitophilus plants that had been mis-identified as C. squarrosus. A total of 27 collections from Texas and 11 collections from Oklahoma were actually Cyperus granitophilus. This means that the true range of Cyperus granitophilus includes both Texas and Oklahoma. All of the specimens of C. granitophilus were found growing on granite outcrops similar to the granite outcrops where the plant is found in the southeastern U.S. Bob and Kim submitted their findings to the Journal of the Botanical Research Institute of Texas and the paper was published in July, 2015.
CITATION: O’Kennon, R.J. & K. Taylor. 2015. Cyperus granitophilus (Cyperaceae), a granite outcrop endemic, new for Texas and Oklahoma (U.S.A.). J. Bot. Res. Inst. Texas 9:251–257.