Flora and Fauna of Northwest Florida

Biology Department

University of West Florida

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Freshwater Marsh and Woodland Swamp

Escambia River Delta

Thompson Bayou

Marshes are part of a larger category of wetlands: partially or periodically submerged lands where the water table is near or above the soil surface. This saturation of the soil causes the sediment to be anaerobic, with oxidized to reduced chemical gradients with depth. Wetlands in general have very low relief (little vertical elevation change) and very little or no wave energy. Water that flows into marshes and swamps from rivers, creeks and bayous, floods out over the marsh surface where the water slows and particles can sediment out onto the marsh surface. Larger debris (detritus & synthetic trash) is also filtered out by trees and plants as storm waters flood wetlands. This natural filtration system adds organic particulate matter to the system.

Organic matter deposited in marshes and swamps from the filtration effect and from resident plant growth tends to accumulate there due to the lack of oxygen. Although there are lots of bacteria in wetland sediments, they cannot "burn up" the organic matter for energy with oxygen and convert to into carbon dioxide. Accumulated organic material will compact over long periods of time and form a peat, and eventually coal and oil deposits.

Along rivers there are flat reaches in the valleys cut by the rivers over long periods of time. These flat areas are the flood plain of the river, locally are vegetated with either marsh plants or cypress, cedar & tupelo trees. Preserving the flood plains of rivers ensures that the filtration process will occur during periods of high water, and helps to maintain water quality in downstream habitats.

The wetland tree species have adapted to living in standing water and unstable anaerobic sediments by having their trunks "buttressed" for support and sending up "knees", parts of their roots, above the flood level for breathing air. Tupelo have special air breathing tissue seen as white spots on their knees called lenticels.

In salt marshes, there is a clear demarcation between the wetland and upland due to the inhibitory effects of salt on most plants. In freshwater wetlands, the transition or ecotone between wetland and upland is not as clear. Regulatory agencies use both physical properties (soil chemistry/appearance) and biological properties (plant species distributions) to "delineate" (determine the boundaries of) wetlands.

Wetlands Delineation:

I. By Soils

Hydric Soils: Water saturated, anaerobic, reduced chemicals (sulfide, methane), black color (FeS).

Wetland soils do not have to be organic-rich (Histosols) peat and muck, although they tend to develop that sediment type over time from organic material accumulation. Some wetlands have a mineral soil (<20-35% organic). In areas where the water table fluctuates a lot, gleys (greenish coloration) and mottles (red) are found in the mineral soil, indicating that the soil has alternated between anaerobic (water saturated wetland) to aerobic (the region above the water table is called the vadose zone) chemistry.


II. By Plants

The adaptations of plants to wetland soils are used to indicate the extent of water saturated conditions, as the plants will provide an "average" view where wetland boundaries change. Those plants that cannot tolerate wetland soils will be eliminated wherever these conditions occur. Some plants have become so well adapted to wetland soil conditions that they are not naturally found anywhere else, or are only rarely found outside of wetlands. These plants are categorized as being Obligate. Some of these plants, like cypress, will do fine if planted and tended in upland sites, but naturally they are restricted to wetland soils, and so are the most useful in determining wetland boundaries. Other plants can tolerate wetland conditions, but also do well in upland sites. These are categorized as being Facultative, and give us no clear distinction for wetland boundaries. An in between category of Facultative Wet is used for those plants that are most abundant in wetlands, but also are regularly found in upland conditions. Hydrophytes are plants for which there is no question as to their wetland status. They are regularly found in standing water as either Submerged (SAV=submerged aquatic vegetation), or emergent (roots/stems in the water, upper parts in the air) vegetation.


Hydrophytes (submerged or emergent)



Yellow Water Lilly


Pickerel Weed

Pontederia cordata

Bull Tongue

Sagitaria lancifolia

Arrow Arum

Peltandra virginica


Cladium jamaicensis

Cattail (narrow)

Typha domingensis


T. latifolia


Cladium jamaicense

Big cordgrass

Spartina cynosuroides


Phragmites australis

Obligate Wet

Bald Cypress

Taxodium distichum

White Cedar

Chamaecyparis thyoides

Water Tupelo

Nyssa biflora

Royal Fern

Osmunda regalis


Orontium aquaticum

Sphagnum Moss

Sphagnum spp.


Pitcher plant

Sarracenia purpurea

Water Sundew

Drosera intermeadia


Pinguicula lutea

Faculatative Wet

Red Titi

Cyrilla racemiflora

Black Titi

Cliftonia monophylla


Azalea spp.

Tulip Poplar

Liriodendrom tulipifera

Red Maple

Acer rubrum

Florida Anise

Illicium floridanum

Chain Fern

Woodwardia virginica

Cinnimon Fern

Osmunda cinnamomea


Sweet Bay Magnolia

Magnolia virginiana

Southern Magnolia

Magnolia grandiflora

Slash Pine

Pinus elliotii

Red Bay

Persea borbonia


Vaccinium spp.


Lyonia lucida