Physiognomy and Structure: These are open woodlands; the trees are primarily needle-leaved evergreen conifers and on loamy soils can be straight, well-formed, and moderately tall. Open canopies and grass-dominated understories are typical of sites managed with prescribed fire. Sites lacking a hardwood midstory were more prevalent prior to the twentieth century.

Floristics: This vegetation is naturally dominated by Pinus palustris. Scrub oaks, such as Quercus marilandica, Quercus incana, Quercus margarettae, Quercus falcata, and sometimes Quercus laevis form a sparse or clumped understory in most stands, in fact in all but the most mesic ones. Low shrubs, mostly ericaceous, may be abundant. East of the Mississippi River, Aristida stricta (in North and South Carolina) or Aristida beyrichiana (from South Carolina to Mississippi) are usually the dominant or at least a characteristic herb. In central South Carolina and west of the Mississippi River, both Aristida beyrichiana and Aristida stricta are absent and various other grasses dominate. Many examples have moderate to high plant species richness, with most of the species in the herb layer. Some mesic associations have high species richness values measured at the 1/10-hectare scale. Forbs, especially composites and legumes, are usually also an important herb component. Some typical mesic to dry-mesic grass species include Andropogon gyrans var. gyrans, Andropogon ternarius, Andropogon virginicus, Panicum virgatum, Schizachyrium scoparium, Schizachyrium tenerum, Sorghastrum elliottii, Sorghastrum nutans, Sorghastrum secundum, Sporobolus clandestinus, and Sporobolus junceus.

Dynamics:  Frequent fire is the predominant natural disturbance of this group, and it is dependent on frequent prescribed fire every 2-3 years. Fires are mostly low to moderate in intensity, removing above-ground vegetation of herbs and shrubs, but have little effect on the fire-tolerant Pinus palustris trees. Vegetation recovers very quickly from fire, with live herbaceous biomass often restored in just a few weeks after a growing season fire. Many plants have their flowering triggered by burning. In the absence of fire, species which are less able to withstand fire increase. Quercus spp. and other shrubs, kept to low density and mostly reduced to shrub size by fire, become tall and dense and can reduce Pinus palustris tree regeneration. Herb layer density and diversity declines in the absence of fire. On most soils, vegetation undergoes substantial structural alteration and reduction in species richness with lack of fire. Canopies are multi-aged, consisting of a fine mosaic of small even-aged patches driven by gap-phase regeneration. Pinus palustris is shade-intolerant and slow to reach reproductive age but is very long-lived, and continues to produce more cones as it grows older, after age 100. 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).