Vegetation Communities of
The Yazoo-Mississippi River Floodplain

Below, I "split hairs" a bit, and provide some detail on the characteristic communities that occur in the "Delta" of northwestern Mississippi. While we could lump these into a main grouping of "wetland bottomlands and swamp forests", variations in soils and hydrology do occur in our flat landscape, and even slight variability can lead to development of unique landscapes. The descriptions that follow are modified from work by Dr. Jim Wiseman (US Army Corps of Engineers) in the '80s.

Ridge Bottom Forests - Occur on better drained sandy loams and loams on major floodplains; Similar in structure to bottomland forests in adjacent loess bluffs. Common canopy species include Quercus michauxii, Q. falcata var. pagodifolia, Q. nigra, Q. phellos, Carya sp., Liquidambar styraciflua.

Sweetgum-Bottomland Oak Forests - Dominated by sweetgum and various wetland oaks. The most common oaks include Quercus phellos, Q. nuttallii, Q. nigra, Q. michauxii, Q. lyrata, Q. muhlenbergii, Q. shumardii. Major associates in these forests include Celtis laevigata, Ulmus americana, and Fraxinus pennsylvanica. Common understory trees and minor associates include Carya aquatica, Ulmus crassfolia, Quercus laurifolia (lower CP), Acer rubrum, A. negundo, Gleditsia triacanthos, Diospyros virginiana, Morus rubra, Cornus spp., Sassafras albidum, Ilex decidua, Lindera benzoin, and rarely, Taxodium distichum

Hardwood Bottomland Forests - These are late successional forest that develop over clay or clay loam flatlands and ridges. Typical canopy species include Quercus lyrata, Q. nuttallii, Q. nigra, Q. falcata var. pagodifolia, Q. michauxii, Ulmus americana, Fraxinus pennsylvanica, Celtis laevigata, Liquidambar styraciflua. Common understory species include Acer negundo, A. rubrum, Asimina triloba, Cornus drummondii, Ilex decidua, Styrax americana, Sabal minor.

Wet Hardwood Bottoms - These communities occur on heavy clay flats and along drainages where the soil can be saturated for much of the year. Common species of the canopy include Quercus nuttallii, Q. lyrata, Carya aquatica, Fraxinus pennsylvanica, Diospyros virginiana, Celtis laevigata , Acer rubrum, Taxodium distichum.

Canebrakes - Occur as understory patches and edge communities in all major forest types in the Delta region; Forest understories are often dominated by a dense, low (2 to 4 meters) thickets of Arundinaria gigantea. This native cane was common on well-drained ridges during settlement times, and evidently grew to enormous proportions in height and diameter (1.5"-2"), not seen today in any extant stands.

Sandbars - These are unstable riparian communities that support grasses, sedges, and annual dicots, and a sparse assemblage of woody species including Salix nigra, S. interior (S. exigua), Populus deltoides, Ilex decidua, Amorpha fruticosa, Bumelia lanuginosa. Our best sandbar systems are seen along the Mississippi River and a few of its tributaries.

Mudbars and Low Sandbars - These are unstable depositional features of rivers and streams. They may be sufficiently persistent in some growing seasons that seedlings of Salix sp. and Populus sp. may develop, but woody plants rarely survive due to submergence. These habitats support opportunistic wetland herbaceous species including Ammania coccinea, Lindernia dubia, Eragrostis glomerata, Fimbrysylis vanlii, Cyperus spp., Eleocharis spp.

Riparian Pioneer Forests - These communities develop on newly accreting land along major and minor stream systems. Black willow (Salix nigra) and cottonwood (Populus deltoides) are by far the most common woody trees in pioneer riperian stands. The most common canopy species are Salix nigra, S. interior, Populus deltoides, Platanus occidentalis, Acer saccharinum, A. negundo, Carya illinoensis, Betula nigra (north Delta), Fraxinum pennsylvanica, Ulmus americana, Liquidambar styraciflua, Celtis laevigata.

Willow Thickets - Almost pure stands of black willow (Salix nigra) form on riparian sites, sloughs and swales to wet to support cottonwood. Some willow thickets also have edge strands of the smaller sandbar willow, giving the thickets a distinct "stratified" appearance. An excellent willow thicket can be seen on the south side of State HW 8 and about 1.5 miles west of the intersection of US HW 49 and HW 8.

Sandfields - These relatively level savanna-like areas form after major flooding by river systems. They are most common along the Mississippi River floodplain and parallel streamcourses. They are remarkable due to their fairly diverse herbaceous flora but low woody flora. Common woody vegetation of the sandfields includes Salix nigra, S. interior, Populus deltoides, Prunus angustifolia, Zanthoxylum clava-herculis, Gleditsia triacanthos, Morus rubra, Forestiera acuminata, Bumelia lanuginosa, Fraxinus pennsyvanica, Ulmus americana, Amorpha fruticosa, Melia azedarach, Albizzia julibrissin, Cornus drummondii, Ilex decidua. As the mostly thorny tree-shrub canopy evolves, these take on the look of savannas. Relatively new sandfields can be accessed by foot at Rosedale at the Great River Road State Park.

Oxbow Swamp - These lowland swamps are formed when rivers change course and leave low curved water courses behind. These areas undergo a normal aquatic succession of open water to marsh to bogland to swamp. Oxbow lakes and swamps are the most common kinds of lentic habitat in the region. May be dominated by either bald cypress or swamp tupelo or both. Swamp tupelo is uncommon in the western side of the Delta. Common woody species include Taxodium distichum, Nyssa aquatica, Cephalanthus occidentalis, Salix nigra, Carya aquatica, Populus heterophylla, Sabal minor. These are common throughout the region - Lake Washington, Lake Bolivar, Moon Lake. Leroy Percy State Park has a very nice oxbow lake as a main feature of the park.

Buttonbush Shrubswamp - Characterized by very sluggish hydrologies and dominated by low-growing shrubs including buttonbush, hibiscus, giant rice cutgrass, duckweeds. Good example seen in the lower reaches of Deer Creek along US Highway 61 south past Valley Park and north of the Yazoo River bridge at Vicksburg.

Water Elm/Swamp Privet Swamps - Water elm (Planera aquatica) and swamp privet (Foresteria acuminata) generally are small streamside floodplain trees or inhabitants of standing water

Backswamps - Occur in swales and sloughs near and usually parallel to major streamcourses. Dominated by Taxodium distichum.

Cypress Strands and Sloughs - Occur along bayou channels; dominated by Taxodium distichum and Cephalanthus occidentalis.

"Barpits" or Borrow Pits - Bowl-like depressions usually flooded and flanked by willows and buttonbush. Result from road and levee construction. Soil was “borrowed” to build road beds and levees.

Abandoned Farmhouse Sites - chinaberry, paper mulberry, mimosa, wild plum, peach, pecan

Railroad Right-Of-Ways - Sassafras, sumac, mimosa, palmetto, black willow

Natural Levees - Formed by periodic flooding of river systems, often very sandy.