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. Floodplains (aka: sweet gum - oak floodplains; wet forests: floodplain hardwood forest; oak-gum floodplain; stream floodplains): Often referred to as bottomlands, floodplains are low laying areas adjacent to the larger creeks, bayous, and rivers which overflow and flood with some regularity. The floodwaters deposit rich alluvial soils, moderately permeable silty, sandy loams that support a wide diversity of vegetation. The major floodplains in the region were formed during the Wisconsin glaciation, when sea levels were low and great rivers cut deep and wide channels in the landscape. These channels are now largely filled with sediment and deposits through which the present day rives, much smaller than in the past, wind and meander. Floodplains often occur in terraces with various swales, ridges, and levees stepping down in tiers to the water level. Some ecologists subdivide these terraces into separate ecosystems, including but not limited to, baygalls on the outer margins of higher terraces, and cypress sloughs in the lowest areas. Pine trees are uncommon or absent in the floodplains, which are dominated by deciduous canopy trees including water oak (Quercus nigra), chestneu or basket oak (Quercus michauxii), willow oak (Quercus phellos), cherrybark oak (Quercus pagoda), and red oak (Quercus falcata). Other important trees include the overcup oak (Quercus lyrata) which can grow in and around standing water, sweetgum (Liquidambar styraciflua), blackgum (Nyssa sylvatica), water