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Grasshopper Hollow

Grasshopper Hollow




Grasshopper Hollow Natural Area is a 593-acre natural area jointly owned by the Mark Twain National Forest, The Nature Conservancy, and Doe Run Mineral Corporation. Located in Reynolds County, Missouri, Grasshopper Hollow contains the largest known fen complex in unglaciated North America. Within this watershed are four fens, a forested fen, ten deep muck fens, and one prairie fen, as well as several state-listed plant and animal species. There is no other site in Missouri, or unglaciated North America, with the diversity of fens and associated species that exist at Grasshopper Hollow. A fen is a rare natural community where soils are saturated from the upwelling of mineral-rich groundwater, creating spring rivulets and ooze areas. Fens experienced a decline in acreage at a rate of about eight percent from 1950 to 1970, mostly from mining and draining for cropland, fuel and fertilizer. Because of the large historical loss of this ecosystem type, remaining fens are that much rarer, and it is crucial to protect them. Because Grasshopper Hollow is the largest known fen complex in unglaciated North America, and contains unique and ecologically important wildlife habitat, this wetland should be considered a national Wetland of Distinction.


  • Protects biologically diverse wetland flora, fauna and/or their habitat
  • Supports significant numbers of wetland-dependent fauna, such as water birds or fish
  • Rare or unique wetland type within its own biogeographical region. (Meeting this criteria would include, but is not limited to, wetlands with unique hydrology or chemistry that make it rare within its own region)


Grasshopper Hollow is controlled by the Nature Conservancy whose mission is “to preserve the plants, animals and natural communities that represent the diversity of life on Earth” by protecting the lands and waters they need to survive. Under this mission, Grasshopper Hollow, represents a rare natural community. This rare, natural community contains unique glacial relict species that are not found in other wetland types within Missouri. That is, they are species that were common in Missouri 10,000 years ago when glaciers covered the upper midwest. In the intervening thousands of years Missouri’s climate has gotten warmer and drier. The glacial relict species were able to persist in fens and along spring branches where cool groundwater provides appropriate habitat conditions. Other glacial relict species in Missouri persist on cool, moist north facing bluffs. Within Grasshopper Hollow’s fens, glacial relicts include the four-toed salamander, wood frog, Riddell’s goldenrod, marsh blue violet, interior sedge, tussock sedge, sweet William phlox, and marsh bellflower. Other non-relict, but notable species include beavers, the rare four-toed salamander and the rare wood frog. In 2000, the federally endangered Hine's Emerald Dragonfly was discovered to be breeding at this site. In short, Grasshopper Hollow, a protected Natural Area, safeguards these unique species. 

Evidence Attached. See: Grasshopper Hollow Complete Plant List


While no vertebrate species are restricted to karst fens, like Grasshopper Hollow, they do provide important habitat components for several species. Many bird and mammal species will utilize karst fens for drinking water and for foraging on invertebrates found there. Bird species are typically associated with the shrub component of karst fens and include the yellow-breasted chat and common yellowthroat. The western slender glass lizard (Ophisaurus attenuatus attenuatus), four-toed salamander (Hemidactylium scutatum), eastern long-tailed salamander (Eurycea longicauda longicauda) and the dark-sided salamander (Eurycea longicauda melanopleura) all utilize fens.

The federally endangered Hine’s emerald dragonfly (Somatochlora hineana) is a karst fen obligate insect. A key component of fen’s supporting this species is the presence of crayfish burrows created by the devil crayfish (Lacunicambarus diogenes). Other Odonates highly associated with karst fens include the grey petaltail (Tachopteryx thoreyi), seepage dancer (Argia bipunctulata), and the yellow-sided skimmer (Libellula flavida). Other Odonates that utilize karst fens include the springwater dancer (Agria plana) and clamp-tipped emerald (Somatochlora tenebrosa).

The swamp metalmark butterfly (Calephelis muticum) is highly associated with karst fens as it utilizes swamp thistle (Cirsium muticum) as a host plant. Phantom crane flies (Bittacomorpha clavipes) are frequently seen utilizing karst fens. The following snail species often utilize fen habitats: the slender walker (Potamiopsis lapidaria), ice thorn (Carychium exile), white snaggletooth (Gastrocopta tappaniana), blade vertigo (Vertigo milium) and toothless column (Columella simplex).

Beaver can also colonize these locations, creating a larger array of niches for other more aquatic species and typical wetland taxa like fish and waterfowl. In addition to the above, many other native insect species are likely associated with this ecological site, especially native bees, ants, beetles, butterflies and moths, and crickets, grasshoppers and katydids. 


Grasshopper Hollow is the largest unglaciated fen complex in North America. Fens are an important and unique wetland type. Fens are peat-forming wetlands that rely on groundwater input and require thousands of years to develop and cannot easily be restored once destroyed. When we think about the size and scope of Missouri’s wetlands, many of them are riverine, driven by hydrology dominated by overland flow. However, Grasshopper Hollow, a fen, is unique to the area and rare across the United States. Accordingly, this wetland should be considered a Wetland of Distinction.

Evidence Attached. See: Grasshopper Hollow NA Nomination

Exemplary Ecosystem Services:
  • Aesthetic/cultural heritage value/provisioning
  • Recreation (birdwatching, ecotourism)
  • Storm abatement
  • Carbon storage
  • Water quality improvement


There is a significant cultural connection to these locations in the Ozarks because they were openings within the forest landscape with water. This mirrored locations in the Appalachians in which Scotch-Irish were moving from and therefore locations like Grasshopper Hollow and other fen complexes were places of early European settlement.


Grasshopper Hollow has a self-guided one-half mile long trail with 10 interpretive stations including an observation deck. A spur of the Ozark Trail borders the natural area. Grasshopper Hollow offers opportunities for flora/fauna observation and photography.  


The discharge of groundwater in karst fens, like Grasshopper Hollow, is very slow and gradual. The velocity is minimal enough that plant roots are able to hold soil and organic matter in place. The build of organic soils over hundreds to thousands of years act as sponge and increases the site’s capacity to hold onto water over time. These attributes contribute to slow discharge of water into the fen and gradual release downstream and contribute to storm abatement for the surrounding catchment. In altered settings elsewhere, ditches concentrate and divert these groundwater flows. The impacts of these actions can be seen after heavy rain events swiftly and dramatically impact adjacent streams with higher and flashier flows. Locations like Grasshopper Hollow contribute to greater stability and persistence of the groundwater table and baseflow of the adjacent headwater stream system.


Fens represent a large array of ecosystem services, including the highest biodiversity found among wetlands, hydrological services, water purification and carbon sequestration. Fens sequester carbon by accumulating undecomposed plant material, referred to as peat, in the soil. Globally, fens store more than 30% of soil carbon, representing a Carbon stock of 400–550 Gt (gigatons). The fact that Grasshopper Hollow is one of the few places with histic/organic soils in Missouri raises the significance of them being important sites for carbon sequestration. Much of the carbon storage that occurs in Missouri, and particularly in the Ozark Highlands is within the aboveground biomass of the forest. However, the permanently saturated conditions within fens prevent decomposition and lead to the belowground accrual of carbon for hundreds to thousands of years. Although these sites might be small compared to the amount of carbon locked up in the adjacent trees, the longevity of carbon storage within karst fens is a magnitude greater.


Groundwater discharging through the thick organic soil, dense root system of wetland plants, and diverse microbiota of karst fens is like a living water filter benefiting the water quality as it moves through the isolated headwater locations where most karst fens are found. The fact that Grasshopper Hollow is the largest unglaciated fen complex means that this location in particular is benefiting the water moving through it.


Conservation status: State/provincial/regional protection

Adjacent Land Use: Upland Forest/Woodland, residential - low density

Approximate natural buffer width: > 100 ft

Other information:

This ecosystem is dominate by water, and hydrological change poses some of the most significant threats. Beaver dams have changed the hydrology in some areas of the fens. The Nature Conservancy is managing the activities of beavers where their dams are significantly altering habitats. Fire management is also used not only to reduce the understory, which historically would have been more open with periodic fires, but to maintain the natural elements of the fen.  

From the junction of Highway A and Highway 72 in Bunker, travel east on Highway 72 approximately 7.6 miles to Forest Service road 860. Forest Service road 860 is 1.0 mile past the intersection of Highway 72 and Highway TT. Turn left (north) on 860 and travel 0.6 miles to the parking lot and trailhead. Visitors can walk the trail that follows an old road to view the fens.


Approximate size: 240 ha (593 acres)
General wetland characterization: Inland Fresh Meadow
Adjacent Water Bod(ies): 
  • Lake
  • Pond
  • Stream
Name of body of water: Grasshopper Hollow is adjacent to Bee Fork and a various unnamed tributaries to Bee Fork.

Surficial Geology:

Primary soil map units within Grasshopper Hollow include:

  • Midco very gravelly loam, 1 to 3 percent slopes, occasionally flooded
  • Batcave-Farewell complex, 0 to 2 percent slopes, frequently flooded
  • Poynor-Clarksville-Scholten complex, 8 to 15 percent slopes, stony
  • Coulstone-Bender complex, 15 to 50 percent slopes, very stony
  • Clarksville-Scholten complex, 15 to 45 percent slopes, very stony


Dominant flora: There are four seep fens at Grasshopper Hollow where you may find a variety of sedges, rushes, grasses, as well as marsh coneflower (Rudbeckia fulgida), royal fern (Osmunda regalis), marsh fern fen goldenrod (Solidago riddellii), Michigan lily (Lilium michiganense), glossy-leaved aster (Aster puniceus var. firmus), Culver’s root (Veronicastrum virginicum), and marsh bellflower (Campanula aparinoides). The mesic zones contain an assortment of plants including prairie cord grass (Spartina pectinata), prairie dock (Silphium terebinthinaceum), big bluestem (Andropogon gerardii), western ironweed (Vernonia baldwinii), and common mountain mint (Pycnanthemum virginianum). The drier sections are dominated by tall goldenrod (Solidago altissima) and broom sedge (Andropogon virginicus). The forested fen at Grasshopper Hollow was heavily cut in the past, but is being restored to its natural quality. Chestnut oak, red maple, hornbeam, green ash, and red elm are the dominant canopy trees with spicebush in the understory. The ground flora, which is concentrated on moss and sedge dominated hummocks, includes swamp agrimony (Agrimonia parviflora), jewelweed (Impatiens capensis), leafy bulrush (Scirpus polyphyllus), golden ragwort (Senecio aurea), and fen goldenrod.

Unique flora: Rare flora at Grasshopper Hollow includes Harebell (Campanula aparinoides), Wild Sweet William (Phlox maculata var. pyramidalis), Tussock Sedge (Carex stricta var. strictior), A Sedge (Carex trichocarpa), Heart-leaved Plaintain (Plantago cordata), Marsh violet (Viola cucullate var. cucullata), and A Sedge (Scirpus polyphyllus). 

Dominant fauna: Yellow-breasted chat, common yellowthroat, eastern long-tailed salamander, dark-sided salamander, crayfish, swamp metalmark butterfly, slender walker, ice thorn, white snaggletooth, toothless column, beaver

Rare fauna: Rare fauna at Grasshopper Hollow includes the four-toed salamander (Hemidactylium scutatum) and the wood frog (Rana sylvaticus)

Fens are wetlands created when calcareous groundwater seeps out to the soil surface and are typically dominated by herbaceous plants kept open by both saturated soils and historically occasional wildfires. The fens in Grasshopper Hollow are created by groundwater moving down through the Gasconade dolomite formation and hitting a resistant layer, likely sandstone, along which the water then runs horizontally and seeps out onto the lower slopes along the valley. Water that feeds these fens originates in the immediate 2,000-acre surface watershed but also from losing streams in the Logan Creek valley to the south, demonstrating the complexity of water movement in karst landscapes.


Fens experienced a decline in acreage at a rate of about eight percent from 1950 to 1970, mostly from mining and draining for cropland, fuel and fertilizer. Because of the large historical loss of this ecosystem type, remaining fens are that much more rare, and it is crucial to protect them. It is important to recognize that while mining and draining these ecosystems provide resources for people, up to 10,000 years are required to form a fen naturally.

Interestingly, fen plant material does not decompose due to growth occurring in saturated, oxygen-free conditions. This undecomposed plant material can provide historical information regarding past plant species composition, and the climate they lived in. In fact, if one were to take a core of a fen, one could reconstruct a time capsule dating back for thousands of years.

Additional Info

Wetland location : SW of Centerville, Missouri (Reynolds County) (37.412200, -91.080900)

Name of Wetland : Grasshopper Hollow


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