Wetlands

Little Bean Marsh natural area

Wetlands are a transition zone between land and aquatic environments, and they protect the quality of both. A rich variety of plants and animals live in wetlands.

As a transition zone between land and a variety of aquatic environments, wetlands share some characteristics of both, yet they have their own unique qualities belonging to neither land (terrestrial) nor water habitats.

One basic definition of a wetland is that it is where the water table — which we usually think of as being below ground — occurs at or near the surface of the land, so that the land is covered by shallow water. As a transition zone between land and aquatic habitats (such as lakes, streams, and rivers), wetlands have one or more of these characteristics:

  • At least periodically, the wetland is dominated by aquatic plants (hydrophytes).
  • The substrate (ground) is predominantly undrained water-saturated or water-covered soil.
  • The substrate, if not technically a soil, is saturated or covered by water at some time during the growing season.

Wetland Natural Communities

Wetlands technically can occur within many other habitat types, including bottomland forests and woodlands, flatwoods, prairies, and stream edges. Many systems for classifying habitats include these as subtypes, but here we will focus on the following wetland natural communities.

Riverine Wetlands

Riverine wetlands are associated with rivers. They occur in a river or stream valley, between the stream channel and the valley edge. They include floodplains, blue holes, sand ponds, oxbows, and sloughs. They are flooded or inundated frequently. Most occur near wet or wet-mesic bottomland forest or wet bottomland prairie. They can vary greatly in terms of water and soil characteristics.

Riverine wetland types include marshes, swamps, and shrub swamps. In Missouri, riverine wetlands occur mainly in the lowlands and floodplains of the Bootheel, along the Missouri and Mississippi rivers, and in northern and western Missouri, especially in the region where the Grand, Chariton, Thompson, and Missouri rivers meet.

Sinkhole Pond Wetlands

Sinkhole ponds occur where the slow, dissolving action of mildly acidic groundwater has enlarged a cave tunnel so much that the cave roof collapses, causing the land above it to sink down. Sometimes, these sinkholes open directly into the cave system below, but other times, they are clogged with surface materials (soil, brush, etc.), and a pond forms.

Sinkhole pond wetlands are usually not connected to other streams or waterways. Instead, they are filled by rainwater, runoff, and/or groundwater. Where does this water go? It either evaporates, or it drains into the cave or the porous karst bedrock below.

Sinkhole pond waters are usually stagnant and hold little dissolved oxygen, and there is usually little water movement. They range from neutral to acidic and offer few available nutrients to plants and other life-forms. As a result, sinkhole ponds host many plants and animals adapted to that special environment that cannot survive in other places.

In Missouri, sinkhole pond wetland communities include pond marshes, pond swamps, and pond shrub swamps. Most of Missouri’s sinkhole pond wetlands occur in the Ozarks, in the southern half of the state, where karst geology predominates, and along the Mississippi River hills.

Groundwater Seepages: Fens and Seeps

Where the land meets the water table, groundwater seeps into the soil, keeping it constantly, or almost constantly, saturated or under water. This infiltration of water occurs in complex patterns, varying with the slope of the land and the shape and types of bedrock beneath the soil.

Because fens and seeps are closely associated with groundwater, the temperature and other characteristics of the water tend to be similar to those of underground water: cool and pH-buffered by limestone and dolomite bedrock. You might think of fens and seeps as essentially very diffuse springs.

Seeps are often quite small; most are less than 5 acres, and many are between 0.1 and 1.0 acre. Size varies with the amount of water being discharged and the local landscape and bedrock. Seeps can occur in upland areas, owing to the way groundwater pools atop a depression in the bedrock below, creating a muddy seep above it.

Fens are a special kind of seep: they are large enough to create gaps in tree canopies (because the saturated ground inhibits tree survival), and they often create an area dominated by sedges and grasses. Fens are also called swampy meadows, wet seepy meadows, or wet calcareous meadows. In Missouri, fens support plants and animals that usually are only found far north of our state — remnants of the last glacier’s retreat.

Some fens produce more vegetation than their cool, low-oxygen, fairly acidic water allows to decay. This buildup of half-decayed dead plant materials eventually becomes peat. The peat itself influences the character of the fen. In Missouri, these accumulations of quaking or soggy ground have been called bogs or shaking springs.

Other characteristics of fens include muck, an organically rich, little-oxygenated soil that is more decomposed than peat, and marl, rocklike deposits of calcium and magnesium that have been precipitated out of the hard groundwater by acidic fen conditions.

Acid seeps are another special type of groundwater seepage. Acid seeps notably occur in the Crowley’s Ridge area near the Bootheel. They host several unusual and interesting plants found nowhere else in the state.

Saline seeps, also called salt springs, mineral springs, or salt licks, occur in the northern half of Missouri, in places where nearby soils contain concentrated alkaline salts and minerals. Water percolates through buried salt deposits and is continually supplied by brackish water. As with acid seeps, saline seeps host a variety of unusual plants not found elsewhere. In this case, ones that can tolerate plenty of salt.

Springs and Spring Branches

These wetland communities have a continuous flow of mineralized groundwater through established fractures or openings such as sinkholes, aquifers, or losing streams. The amount of flow can vary, but water chemistry and temperature are relatively constant. The cool water strongly influences the types of aquatic animals that live in these habitats.

Many kinds of aquatic plants and animals live in spring and spring branch wetlands. In Missouri, limestone and dolomite springs occur mostly in the Ozarks.

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Photo of Dome Rock at Pickle Springs NA
Sainte Genevieve
Pickle Springs Natural Area is a geological wonderland with scenic waterfalls and cool box cany
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Photo of several cattail flowering stalks
Species Types
Scientific Name
Typha spp.
Description
Missouri’s cattails are all tall wetland plants with narrow, upright leaves emerging from a thick base, and a central stalk bearing a brown, sausage-shaped flower spike.
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Photo of path rush, closeup showing drying fruits.
Species Types
Scientific Name
Juncus spp. and Luzula spp.
Description
Missouri has 24 species in the rush family. Distinguishing between these grasslike plants can be tricky, but it’s easy to learn some basics about the group.
Media
Photo of eastern woodland sedge plant growing among leaf litter.
Species Types
Scientific Name
Carex, Schoenoplectus, Scirpus, and other genera
Description
Missouri has more than 200 species in the sedge family. Distinguishing between these grasslike plants can be difficult, but it’s easy to learn some basics about the group.
Media
Photo of southern blue flag iris plants with flowers
Species Types
Scientific Name
Iris virginica
Description
Ten species of iris grow wild in our state, but only four of them are native. Of our native irises, this one is the most common. But drainage “improvements” are eliminating the habitat of this beautiful wetland wildflower.
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Photo of water lily pads and flowers on a pond
Species Types
Scientific Name
Nymphaea spp.
Description
Water lilies are among the most beautiful of all water plants. They have large, round leaves 8–16 inches across, each with a single V-shaped notch.
Media
Illustration of bald cypress leaves and cones.
Species Types
Scientific Name
Taxodium distichum
Description
Bald cypress is an “evergreen” tree that is not evergreen! Like the leaves of hardwoods, its needles turn yellow in the fall and are shed. A tree associated with dark, mysterious swamps, its impressive form also graces many public landscapes.
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Illustration of black gum flowers and fruits.
Species Types
Scientific Name
Nyssa sylvatica
Description
A close relative of water tupelo, black gum is growing in popularity as a landscaping tree. In the wild, it’s usually found in the Ozarks and Bootheel, but with people planting it in their yards, you might find it anywhere in the state.
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willow
Species Types
Scientific Name
Salix spp. (about 12 species in Missouri)
Description
Exotic willows are available at lawn and garden centers, but there are several willow species that are native to Missouri. Most are rather humble colonizers of gravel bars, riverbanks, and lakesides. Many are important for human economic interests. All have a place in our wild ecosystems.
Media
Photo of a spothanded crayfish viewed from above on white background.
Species Types
Scientific Name
About 36 species in Missouri
Description
Crayfish are freshwater aquatic invertebrates that look a lot like small lobsters, to which they are related. There are about 36 species of crayfish in Missouri.
Media
Photo of a male Banded Pennant dragonfly
Species Types
Scientific Name
Species in the suborder Anisoptera
Description
Like damselflies, dragonflies have long bodies, two pairs of long, membranous, finely veined wings, and predaceous aquatic larvae. Dragonflies typically hold their wings stretched outward, horizontally.
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pond mussel
Species Types
Scientific Name
Bivalve molluscs in order Unionoida
Description
Secretive and seldom seen, freshwater mussels are extraordinarily diverse in Missouri. We have nearly 70 species within our borders. Many are declining, and several are endangered.
Media
image of a Midge
Species Types
Scientific Name
Nearly 1,100 species in North America
Description
Midges are dainty flies that resemble mosquitoes. They often dance together in the air in huge swarms. Unlike their problematic cousins, they are harmless and do not bite.
Media
mosquito resting on a white fabric
Species Types
Scientific Name
About 50 species of mosquitoes in Missouri
Description
Mosquitoes are small flies that look a lot like their cousins in the fly family, the crane flies and midges. Female mosquitoes, however, drink blood from vertebrate animals.
Media
Photo of a single water strider
Species Types
Scientific Name
Aquarius remigis; also species in the genus Gerris
Description
Water striders are hard not to notice. Water-repellant hairs on the hind and middle legs allow these nimble insects to skate on the surface of the water.
Media
Fathead minnow side view photo with black background
Species Types
Scientific Name
Pimephales promelas
Description
The fathead minnow has a blunt, rounded snout, rounded fins, a dusky stripe along the side, and a spot at the base of the tail fin. It is most abundant in pools of small prairie creeks because it tolerates rather high temperatures, extreme turbidity, and low oxygen.
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Golden shiner male, side view photo with black background
Species Types
Scientific Name
Notemigonus crysoleucas
Description
The golden shiner is a deep-bodied minnow with a greenish-olive back and a faint dusky stripe along the midline. It has a fleshy keel along the midline of the belly. It is widespread in Missouri.
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Swamp darter side view photo with black background
Species Types
Scientific Name
Etheostoma fusiforme
Description
Unlike most other darters, the swamp darter prefers swamps and sloughs with no current at all. Rare in our state, it’s found only in a few southeast Missouri locations.
Media
Image of a green treefrog
Species Types
Scientific Name
Hyla cinerea
Description
The bright green treefrog hides perfectly among cattail leaves, where it rests until evening. Then it begins hunting for insects.
Media
Image of a green frog
Species Types
Scientific Name
Lithobates clamitans (formerly Rana clamitans)
Description
The green frog looks similar to a bullfrog but is smaller and has a ridge of skin along the sides of the back that is not found on bullfrogs. It is a game animal in Missouri.
Media
Image of a northern leopard frog
Species Types
Scientific Name
Lithobates pipiens
Description
The northern leopard frog is a medium-sized frog with dark spots on the back. Two skin folds run down each side of the back. In Missouri, it only occurs in our northwestern counties.
Media
Photo of a southern leopard frog.
Species Types
Scientific Name
Lithobates sphenocephalus (formerly Rana sphenocephala)
Description
The attractively spotted southern leopard frog is an excellent jumper and quickly leaps into water when startled. The males’ chuckling calls entertain us even as they function to attract females for breeding. Found statewide except for the northwestern corner.
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Spring Peeper
Species Types
Scientific Name
Pseudacris crucifer
Description
The voices of spring peepers are a true announcement that winter is ending. These small, slender frogs can be several overall colors, but seeing an X on the back is a good way to ensure your identification.
Media
Photo of a central newt adult on a plastic aquarium plant.
Species Types
Scientific Name
Notophthalmus viridescens louisianensis
Description
A small, olive-brown salamander with a fascinating life cycle, the central newt lives in and around woodland ponds and swamps in all but our far northwestern counties.
Media
Image of a spotted salamander
Species Types
Scientific Name
Ambystoma maculatum
Description
A dancing salamander? Hundreds of them all at once? In the water? That’s how spotted salamanders create their next generation, in only a few springtime evenings each year.
Media
Photo of a three-toed amphiuma in an aquarium.
Species Types
Scientific Name
Amphiuma tridactylum
Description
The three-toed amphiuma is an eel-like, completely aquatic salamander. It has very small fore- and hind limbs, each with three very small toes. In Missouri it’s found only in the Bootheel region.
Media
Image of a broad-banded watersnake
Species Types
Scientific Name
Nerodia fasciata confluens
Description
The broad-banded watersnake is a beautiful semiaquatic snake with broad, irregularly shaped bands that can be brown, red-brown, or black and are separated by yellow and gray. This nonvenomous species is restricted to the southeastern corner of the state.
Media
midland brownsnake
Species Types
Scientific Name
Storeria dekayi wrightorum
Description
The midland brownsnake is a small, secretive species that prefers moist environments. It can be gray to brown to reddish brown, and it usually has a tan stripe running down the back, bordered by two rows of small brown spots. The top of the head is usually dark.
Media
Image of a northern cottonmouth
Species Types
Scientific Name
Agkistrodon piscivorus
Description
The cottonmouth is named for the cotton-white lining of its mouth, which it opens wildely when alarmed. This dangerously venomous, semiaquatic snake occurs in the southeastern corner of Missouri, with a spotty distribution in the Ozark Region.
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Photo of a northern watersnake rearing back in grass on land.
Species Types
Scientific Name
Nerodia sipedon sipedon
Description
The northern watersnake is gray to reddish brown with dark brown crossbands. The belly is cream-colored with black and reddish half-moon markings. This is Missouri’s most common watersnake.
Media
Image of a blanding's turtle
Species Types
Scientific Name
Emydoidea blandingii
Description
Blanding’s turtle has an oval, moderately high-domed upper shell and a long head and neck. This medium-sized turtle is endangered in Missouri.
Media
Image of a red-eared slider
Species Types
Scientific Name
Trachemys scripta elegans
Description
An attractive turtle with yellow pinstripes and red ears, this species is commonly seen basking on logs or rocks—until you get too close, and they slide into the water.
Media
Photo of a snapping turtle walking on land with algae on shell.
Species Types
Scientific Name
Chelydra serpentina
Description
A large aquatic turtle with a big pointed head, long thick tail, and small lower shell, the snapping turtle is common throughout the state, anywhere there is permanent water.
Media
Photo of great blue heron
Species Types
Scientific Name
Ardea herodias
Description
This large, graceful, blue-gray bird with a black, plumed eye line has long legs for wading and a slender neck and spearlike bill for catching fish.
Media
Photo of a great egret
Species Types
Scientific Name
Ardea alba
Description
Great egrets are large, white herons with yellow bills and black legs and feet. Market demand for their lovely breeding plumes, and unregulated hunting, nearly made them extinct.
Media
Photo of a least bittern male walking.
Species Types
Scientific Name
Ixobrychus exilis
Description
One of the smallest herons in the world, the least bittern is about as big as a pigeon. It’s nearly impossible to locate when it hides in a cattail marsh. Most see it only in flight.
Media
Photo of a Virginia rail walking on tamped-down aquatic vegetation.
Species Types
Scientific Name
Rallus limicola
Description
A chickenlike marsh bird with a long, slightly curving bill, the Virginia rail is a migratory gamebird related to coots and gallinules.
Media
Photo of a male common yellowthroat
Species Types
Scientific Name
Geothlypis trichas
Description
The male common yellowthroat wears a black mask that contrasts strongly against the bright yellow underparts. The female is olive brown. A common summer resident in Missouri’s marshes and other wet areas.
Media
Photo of a male red-winged blackbird singing
Species Types
Scientific Name
Agelaius phoeniceus
Description
These crimson-shouldered residents of marshes, wet meadows and weedy roadside ditches are well-known by most rural Missourians. Their “konk-o-REEE” song likely emanates from every pond in Missouri.
Media
Image of a swamp sparrow
Species Types
Scientific Name
Melospiza georgiana
Description
The swamp sparrow is an uncommon winter resident in most of Missouri, but as the name indicates it may be more easily found in wet areas.
Media
Photo of an American coot.
Species Types
Scientific Name
Fulica americana
Description
Although it floats like a duck, the American coot is actually in the rail family. Note its short tail and wings, pointed white bill, chickenlike walk, and toes with scalloped lobes.
Media
Photo of Canada goose swimming
Species Types
Scientific Name
Branta canadensis
Description
Canada geese are recognizable by their brownish bodies, black necks and heads, and a distinctive broad white patch that runs beneath their heads from ear to ear.
Media
photo of a wood duck
Species Types
Scientific Name
Aix sponsa
Description
The wood duck is one of the world's most beautiful waterfowl. It is equally famous for being a cavity nester in hollow trees, sometimes 60 feet above the ground and a mile away from water.
Media
Photograph of a muskrat standing on grass
Species Types
Scientific Name
Ondatra zibethicus
Description
The common muskrat is one of the most abundant commercial furbearers in Missouri. This semiaquatic rodent has benefited from the construction of thousands of farm ponds throughout the state.
Media
Nutria in wetland habitat
Species Types
Scientific Name
Myocastor coypus
Description
Nutria are large aquatic rodents native to South America. They were brought to the U.S. for the fur market. In Missouri, nutria are sometimes trapped in the southeastern part of the state.
Media
Image of a swamp rabbit
Species Types
Scientific Name
Sylvilagus aquaticus
Description
Larger and yellower than the eastern cottontail, the swamp rabbit is confined to swamps of Missouri’s Bootheel. As a wetland dweller, it’s a good swimmer and diver, but lack of swamp habitat is making this rabbit’s numbers decline.
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