Plants

The vegetation of a particular region consists of all of its native plant species, as well as those that are introduced and naturalized. The term “flora” is used in a slightly different sense and refers only to naturally occurring plant species. As a rule, plant life, whether in terms of “vegetation” or “flora,” refers to vascular plants, those containing vascular tissue. In South Carolina, these include the ferns (vascular plants reproducing by spores) and their relatives (horsetails and club mosses); gymnosperms, represented by conifers such as pines and cypresses (plants producing seeds but not flowers); and the largest group, by far, the flowering plants.

South Carolina’s vegetation consists of approximately three thousand species. Considering the geographic size of the state, this is one of the most diverse parts of the entire nation. Georgia and North Carolina each boast greater numbers of species, which would be expected for their larger geographic sizes. The apparent high amount of botanical diversity within South Carolina may be explained through its extraordinary representation of natural habitats, which accounts for naturally occurring vegetation, but also through the easy influx of new introductions, many of which become permanent residents. Unfortunately, the influx of alien plant species into South Carolina, which is mostly the result of human activities, accounts for some serious weedy species that have had dramatic economic impacts on the state.

South Carolina may conveniently be divided into four major physiographic provinces, and these are more or less consistent with characteristic vegetation types. The smallest province is that of the Blue Ridge Escarpment, limited to the highest portions of Oconee, Pickens, and Greenville Counties. This area shows considerable affinity toward the vegetation of the Blue Ridge and Appalachian Mountains and even New England, thus affording habitat for southern extensions of many “northern” plant species. Steep topography and dramatic relief are featured in many sites. Elevation ranges vary from river bottoms upward to open granitic domes and, in some places, sheer cliffs. Among the characteristic species at the state’s highest mesic sites are assemblages of white pine (Pinus strobus) and hemlock (Tsuga canadensis), often with diverse mixtures of oaks, hickories, deciduous magnolias, and other hardwoods. Other sites in the mountains, especially those on southern (warmer and drier) exposures, may be dominated by low, shrubby vegetation consisting of many species in the heath (or blueberry) family. Although this is the smallest province, it harbors the state’s highest localized areas of rare species. One of the rarest orchids in North America, Isotria medeoloides, is known from a few spots in the state’s mountains.

The Piedmont consists of a broad band of counties between the mountains and the central part of the state. This area is dominated by gently sloping landscapes, punctuated in places by isolated monadnocks, which suggest small mountain “islands” on a flatter landscape. The soils of the Piedmont were largely ravaged by the excesses of cotton farming throughout the nineteenth century. On the other hand, some excellent examples of naturally occurring Piedmont natural communities remain, countering the notion that this province is of little botanical interest. Strong evidence exists for the existence of southeastern grass-dominated prairies in parts of the Piedmont, these harboring many examples of rare and threatened species. One of these plants is a native sunflower (Helianthus schweinitzii ), which is known in the world only from the two Carolinas. As well, significant stands of bottomland hardwood forest exist along various stretches of Piedmont rivers, these commonly dominated by sycamore (Platanus occidentalis) as well as an assortment of ash species, birches, oaks, and maples.

The Sandhill region is a relatively narrow strip of land stretching from Aiken County northeast through Chesterfield County. This region embraces the fall zone, a geologically distinctive phenomenon representing the first rapids (and boulders) encountered along rivers from the coast, while traveling inland. The Sandhills have a historic reputation of being barren and uninteresting botanically; recent studies have proved much the contrary. Although characterized by deep sandy deposits, the Sandhills contain fascinating wet- land ecosystems as well. Fort Jackson Military Installation in Richland County, for instance, features uncommon diversity and rare plant species, somewhat paradoxical given its proximity to a large metropolitan area. In the early 1990s botanists discovered a large population of one of the world’s most restricted species, rough-leaved loosestrife (Lysimachia asperulaefolia), within an open sandhill seepage bog in Richland County. Prior to this discovery, the plant had been known, and apparently extirpated, from a single site in Florence County.

The largest province is that of the coastal plain. This is a relatively recent formation of gently sloping terraces, dominated by sandy, acidic soils. The coastal plain is deeply cut through by a series of river channels, and extraordinary examples of historically known bottomland hardwood ecosystems are known. Characteristic tree components of these swamps and bottomlands are bald cypress (Taxodium distichum) and water tupelo (Nyssa aquatica). Bottomland forests can be highly diverse: the old-growth portions of Congaree National Park boasts some of the highest tree and woody vine diversity, for its size, in North America, easily rivaling the rainforests of the Pacific Northwest. Much of the coastal plain has been developed for agriculture, but significant natural vegetation remains. Many of these ecosystems developed as a response to periodic fires. For example, most of the area now represented by the coastal plain was historically dominated by longleaf pine (Pinus palustris), a fire- dependent species. Naturally occurring longleaf flatwoods and savannas dominated extensive portions of the outer coastal plain. Sadly, few intact examples of these extremely diverse habitats remain, largely due to urbanization and fire suppression. Additional and recent research has demonstrated intact ecosystems and rare plant species remaining in good examples of Carolina bays, as well as the pocosins. Plant communities of the latter depend on periodic fire and tend to be dominated by pond pine (Pinus serotina), hollies (especially the gallberries, Ilex coriacea and I. glabra), blueberries, and other members of the heath family. Pocosin systems in South Carolina are largely restricted to the Pee Dee portion of the coastal plain, with excellent intact examples at Lewis Ocean Bay Heritage Preserve, near Myrtle Beach. This site is also noteworthy as one of the few remaining localities in the state for Venus’s-flytrap (Dionaea muscipula). The outer edges of the coastal plain deserve special consideration: these areas include the estuaries, sounds, maritime forests, and barrier islands that are increasingly threatened by human activity and development. Along the state’s upper coastline, within the Grand Strand, dwarf pigweed (Amaranthus pumilus) may be found on fore dunes, an example of a threatened species that reaches its southern geographic limit in South Carolina.

Any consideration of South Carolina’s naturally occurring flora must include some treatment of the threats to its integrity. These threats come from two sources. First, human development and manipulation of existing natural areas have constituted an ever-increasing threat to stable natural ecosystems since the seventeenth century. Urbanization has clearly resulted in significant loss of many naturally occurring plant communities and, thereby, a resultant loss of plant diversity. The second threat to the state’s flora comes from aggressive, introduced plant species from other parts of the world. These aliens, once naturalized, essentially become a part of the surrounding landscapes and are then considered “naturalized.” Naturalization of such invaders is sometimes a seemingly irreversible situation. For instance, Japanese honeysuckle (Lonicera japonica) was introduced into North America as an ornamental vine, probably numerous times, beginning in the early nineteenth century. This species is particularly troublesome in the Southeast, and in every county of South Carolina, due to its aggressive ability to cover vegetation and eventually shade out (and kill) its neighbors. There are many other examples of such unwelcome invaders, some of which are notorious as agricultural weeds, causing much damage from the standpoint of expensive control measures, which are often based on herbicides or chemical treatments. Initial establishment of a noxious weedy species is almost invariably the result of human activity, but secondary invasions may occur as well. In the case of Japanese honey- suckle, enough notoriety has been generated about it that gardeners tend not to grow it intentionally, but birds readily move the seeds from place to place after eating the fruits.

Despite the past botanical studies in South Carolina, new species continue to be discovered in the wild. For instance, a new species of native ragweed has recently been discovered on granitic rocks in a few places in the state’s mountains. In the Sandhills an unusual aster that deserves recognition as a new species has been located along some blackwater streams. The discovery and description of species new to science seems paradoxical, in light of the enormous effects of human development throughout the state. Nevertheless, the fact that new species continue to be described suggests a diverse and resilient flora.

Barry, John M. Natural Vegetation of South Carolina. Columbia: University of South Carolina Press, 1980.

Nelson, John B. The Natural Communities of South Carolina. Columbia: South Carolina Wildlife and Marine Resources Department, 1986.

Radford, Albert E., Harry E. Ahles, and C. Ritchie Bell. Manual of the Vascular Flora of the Carolinas. Chapel Hill: University of North Carolina Press, 1968.