Physiognomy and Structure: Stands of this group are naturally open woodlands or savannas, dominated by tall evergreen needle-leaved trees. Without frequent fire, broad-leaved trees and shrubs may occupy more of the midstory of the stand.

Floristics: Stands of this group naturally occur as woodlands or savannas dominated by Pinus palustris or, less frequently, by Pinus serotina, Pinus elliottii, or some combination of these. Hardwood trees are present in any abundance only if composition has been altered by the lack of fire. Shrub cover is patchy and variable. The ground cover is a dense combination of herbs (grasses and forbs) and low shrubs. A variety of ericaceous shrubs and Ilex spp. is common, with their height and density determined by time since most recent fire. Shrubs may include Quercus geminata, Quercus minima, Quercus pumila, Serenoa repens, Cyrilla racemiflora, Ilex coriacea, Ilex glabra, Ilex vomitoria, Vaccinium darrowii, Vaccinium myrsinites, and Lyonia lucida, as well as Morella cerifera and Baccharis halimifolia in near-coastal habitats. Grasses naturally dominate the ground cover (Streng et al. 1993). Aristida stricta or Aristida beyrichiana often dominate within their ranges, but Ctenium aromaticum, Muhlenbergia expansa, Schizachyrium scoparium, other Schizachyrium spp., Sporobolus floridanus, Sporobolus pinetorum, Sporobolus teretifolius, Dichanthelium spp., Andropogon capillipes, other Andropogon spp., and/or other grasses and sedges, including Rhynchospora spp. may also dominate. A great diversity of other herbs is often present, including composites, legumes, insectivorous plants, and variety of showy forbs. Some forbs may include Symphyotrichum spp., Helianthus spp., Liatris spp., Carphephorus spp., Solidago spp., Tephrosia spp., Crotalaria spp., Rhynchosia spp., Baptisia spp., Agalinis spp., as well as Sarracenia spp., Polygala spp., and many others. The vegetation of this group is highly diverse and variable; the dominant species in the overstory and ground cover change across the Southeastern Coastal Plain, with the dominant species frequently not overwhelmingly dominant and therefore a number of species may share dominance, and in addition there is a high level of endemism among the dominant species in a given area. Lack of fire and past overgrazing have limited grass dominance, and the most common species often are shrubs, both native, such as Ilex coriacea, Ilex glabra, and Morella cerifera, and invasive exotic plant species, such as Ligustrum sinense and Triadica sebifera. Other non-native plant species include climbing ferns Lygodium japonicum and Lygodium microphyllum (Platt and Gottschalk 2001, Platt et al. 2006b, Leichty et al. 2011).

Dynamics:  Exposure to frequent, low-intensity fires in the transition from dry springs to wet summers (with a short fire-return interval ranging typically from 1 to 2 years, and less commonly to 3 or 4 years) (Huffman et al. 2004, Beckage et al. 2009, Slocum et al. 2010) is the dominant natural ecological process structuring the savanna physiognomy (Gilliam et al. 2006) and along with hurricanes, influencing the local biodiversity (Platt et al. 2006b). In some parts of the coastal plain, this vegetation historically constituted one of the most extensive types in the region. Widespread alterations, which followed European settlement, including changes to natural fire regimes, have produced drastic changes to this group, and few large examples are extant that are managed using historical fire regimes (e.g., Platt et al. 2006b).

Frequent fire, historically caused by lightning and by people, is the predominant natural disturbance of this group and is crucial in maintaining its open structure and composition. Communities naturally burned every few years, many averaging as often as every 1 to 2 years. Fires are naturally low to moderate in intensity. They burn above-ground parts of herbs and shrubs but have little effect on the fire-tolerant Pinus spp. trees, except for seedlings. It is the frequent fire that keeps these communities open savanna. Vegetation recovers very quickly from fire during the growing season, with plants reappearing in just a few weeks, most prominently in the finer-textured soils. Many plants have their flowering triggered by burning (Platt et al. 1988). In the absence of fire, the shrubs increase and hardwoods invade, their seeds brought in by birds (Hinman et al. 2008). Herb layer density and diversity decline after just a couple of years without fire. In natural condition, examples are generally open with a variety of low-shrub and grass species forming a dense ground cover. Frequent, low-intensity fire was the dominant natural ecological disturbance. Natural stochastic variation in fire was likely important, as was the relative flammability of the vegetation, in determining the relative intensity of fire and its effects on vegetation at a local scale (Beckage et al. 2009, Gagnon et al. 2010). At present, many areas have undergone long periods of time without fire, and this has resulted in greater dominance by shrubs, such as Ilex coriacea, Ilex glabra, Morella cerifera, and Serenoa repens, as well as denser canopies of Acer rubrum and Pinus elliottii var. elliottii rather than Pinus palustris (Huffman and Judd 1998, Noel et al. 1998).

Under natural conditions, the overstories were multi-aged (Platt et al. 1988), consisting of a fine mosaic of small even-aged groves driven by gap-phase regeneration and hurricanes that opened stands periodically (Platt and Rathbun 1993, Noel et al. 1998, Gilliam et al. 2006). Longleaf pine is shade-intolerant and slow to reach reproductive age but is very long-lived, with some trees in old-growth stands 200-500 years of age (West et al. 1993). Many herbaceous perennial plants live a long time and flower in response to fire. Other plants persist as dormant seeds which germinate after fire or after hurricanes open stands. The Federally endangered red-cockaded woodpecker (Picoides borealis) nests in older but live trees of Pinus palustris. Wet-mesic longleaf pine woodlands support many reptile and amphibian species. Some insect populations recolonize burned areas from nearby unburned patches. Sites managed with late spring or growing season prescribed fire provide high arthropod biomass (James et al. 2001, Taylor 2003).

The unifying feature of this group is wet mineral soils associated with a high frequency of fire. Variation in soil texture appears to be a primary driver of differences among associations within the group, with biogeography also important. Communities in this group are often very high in species richness, with some of the highest values measured anywhere at the 1/10-hectare, 1/100-hectare, and 1-square-meter levels (Peet and Allard 1993). However, some associations are naturally low to moderate in species richness.