West Gulf Coastal Plain Seepage Swamp and Baygall

Geology

May occur on a range of geological formations, including intermediate to high Pleistocene terraces, Eocene sands, the Catahoula Formation, and the Wilcox Formation.

Landform

Occupies low landscape positions typically along low gradient creeks, headwaters of drainages, or local depressions, often where underground water flow exits to the surface as a seep.

Soils

Typically sandy to loamy soils, often with an impermeable subsurface layer that restricts water percolation. These sites are typically semi-permanently saturated. These are typically soils of medium to strong acidity, with low available nutrients, and significant organic accumulation.

Parent Description

This system typically occurs as densely wooded sites, characterized by overstory species such as Magnolia virginiana (sweetbay), Nyssa biflora (swamp tupelo), and Acer rubrum (red maple). Other species in the overstory may include Fraxinus pennsylvanica (green ash), Quercus nigra (water oak), Liquidambar styraciflua (sweetgum), and Quercus laurifolia (laurel oak). A well-developed woody understory is often present and includes species such as Morella caroliniensis (evergreen bayberry), Itea virginica (Virginia sweetspire), Persea palustris (swamp redbay), Rhododendron prinophyllum (early azalea), Rhododendron canescens (mountain azalea), Ilex decidua (possumhaw), Vaccinium fuscatum (Arkansas blueberry), Ilex opaca (American holly), Toxicodendron vernix (poison sumac), Viburnum nudum (possumhaw viburnum), Morella cerifera (wax-myrtle), Alnus serrulata (smooth alder), Smilax laurifolia (bamboo-vine), and Vitis rotundifolia (muscadine grape). Southern expressions of the type may also have Ilex coriacea (bay-gall bush) or Cyrilla racemiflora (leatherwood). The herbaceous layer is often dominated by ferns such as Woodwardia areolata (chain fern), Osmunda regalis (royal fern), Osmunda cinnamomea (cinnamon fern), and Athyrium filix-femina (common ladyfern). Carex spp. (sedges), Rhynchospora spp. (beaksedges), and Eleocharis spp. (spikerushes) are also frequently encountered. Sphagnum spp. (sphagnum) occurs in patches throughout, and other bryophytes are common. The rare species Bartonia texana (Texas screwstem) may be encountered in this system, along with other interesting forbs such as Burmannia biflora (northern bluethread) and Apteria aphylla (nodding-nixie).