杓兰
Slope forests (aka: beech-magnolia-loblolly slopes; mesic upland forests: lower slope hardwood pine forest; beech-magnolia-loblolly pine association): Slope forest have a wide mix of conifers, deciduous, and evergreen broad-leaved trees occupying the gentle slopes between the wet bottomlands and the dryer uplands. Small spring-fed streams drain the slopes before reaching the larger creeks. The closed canopy filters the light reaching the forest floor where an ample layer of leaf litter holds water, creating a mesic understory. The soils are relatively fertile with fine, loamy, sands and are well to moderately drained. The purest examples of slope forest are found on the soils of the Willis Formation with red clay in Jasper, Newton, Polk, and Tyler counties, but they extend well into the lower, southern regions where soils and topography are suitable, particularly along the slopes of the waterways. A variety of trees co-dominate slope forest and these can vary with elevation and moisture. In higher and less humid areas, forest shortleaf pine ("Pinus echinata"), loblolly pine ("Pinus taeda"), white oak ("Quercus alba"), and southern red oak ("Quercus falcata") co-dominate, but sweetgum ("Liquidambar styraciflua") and blackgum ("Nyssa sylvatica") are also common. More humid areas tend to shift to American beech ("Fagus grandifolia"), southern magnolia ("Magnolia grandiflora"), and American holly ("Ilex opaca") co-dominating with loblolly pine ("Pinus taeda"), but include a wide variety of other hardwoods such as white oak ("Quercus alba") and sugar maple ("Acer saccharum"). In the lowest, flatter areas of the south, beech trees tend to drop out and are replaced by chestnut oak or basket oak ("Quercus michauxii") and laurel oak ("Quercus laurifolia"). Understory trees and shrubs include Hercules-club or toothache tree ("Zanthoxylum clava-herculis"), hoary azalea ("Rhododendron canescens"), redbud ("Cercis canadensis"), and silver bell ("Halesia diptera"). A rich diversity of wildflowers are found in slope forest such as three jack-in-the pulpits ("Arisaema dracontium", "A. quinatum", "A. triphyllum"), Indian pipe ("Monotropa uniflora"), and wake-robin ("Trillium gracile"). Orchids include the yellow lady's-slipper ("Cypripedium calceolus"), spring coral-root ("Corallorhiza wisteriana"), whorled pogonia ("Isotria verticillata"), southern twayblade ("Listera australis"), crippled crane fly ("Tipularia discolor"), and three birds ("Triphora trianthophora"). Wildfires are much less important to the ecology of the humid slope forest than in the uplands and sandylands, both of which will slowly revert into slope forest when fire is suppressed and slope vegetation that is not tolerant of fire takes hold and fills in the open areas.