Big Thicket

Geological formations (diagonal center) of the Big Thicket Basin and the epochs in which they were formed (lower right).[15][11][16] This is a generalized illustration and it is not accurate in scale or proportion.

Geology: What makes the Big Thicket a remarkable place is the unusually high diversity of plants concentrated in a relatively small area. A major factor enabling this diversity is an unusually high diversity of soils. The exposed surface soils are relatively recent, late Cenozoic Era, predominantly Miocene, Pliocene, Pleistocene, and Holocene Epoch formations. Other than some slight and uniform tilting, the strata are not greatly deformed. The strata were laid down in several cycles of glaciations and warmer interglacial interludes. Although glaciers never extended as far south as Texas, it was during these cold periods that enough water was frozen in polar regions to lower sea levels and the Big Thicket area was dry land well above sea level. Conversely, during the warmer interludes, enough ice melted to increase sea levels and submerge Southeast Texas in the sea. It was during those warmer periods of submersion that alluvial and delta deposits from the streams and rivers of the continent laid down the succession of strata, each new layer burying and compacting the previous. At some point there was an approximately 1% tilting of the layers. Some say it was caused by the rising of the Rocky Mountains,[15] while others say it was the weight of the successive deposits that eventually caused the Gulf of Mexico to subside.[11] The older Pliocene, Miocene, and Oligocene formations are exposed in the north (Polk, San Jacinto, and Tyler counties), while the more recent Quaternary Period formations are exposed in the south (Hardin and Liberty counties).[11][15][16]

Soils: The soils of the various formations at the surface have shifted and intermingled through erosion and other factors over time and can be locally quite complex. The Big Thicket contains a greater variety of soils than any area of comparable size in the United States. Sources vary, but from 50 to 100 soil types are said to occur in Hardin County alone.[6][11] The surface soils tend to be slightly to strongly acidic, and only occasionally neutral in much of the Big Thicket Basin. However, calcareous or alkaline soils do occur in the region, particularly along the Trinity River, in the Beaumont Formation to the south, the Fleming Formation to the north, and northern areas of the Willis Formation where the layer is thin and erosion and road cuts have exposed the Fleming Formation. Most plants are sensitive to soil pH levels (acidic, neutral, or alkaline) and many species will only grow in areas with a specific soil type.[6][11] Claude A. McLeod's study stated that the Big Thicket was "an edaphicmesophytic climax forest" – edaphic, meaning the soil is a greater influence on the plants than the climate, and mesophytic meaning a medium moisture level.[13]

Texas county map with five interpretations of the Big Thicket: *Dark green area = Traditional "Hunter's Thicket"[6] *Light green area = Biological survey[12] *Solid black line = Ecological analysis[13] *Dotted black line = Primitive Big Thicket Region[5] *Solid red line = Big Thicket Basin, geological/ecological analysis[11]

Topography: The Big Thicket Basin has been described as shallow bowl or dish, tilted to one side, with the high rim on the interior north and low rim on the coastal south. Eastern and western rims consist of the low ridges that divide the Neches River and Sabine River drainages on the east and the Neches River and Trinity River drainages on the west. Elevations range from about 350 feet (110 m) in the north to 25–35 feet (7.6–10.7 m) in the south, dropping as low as 3 feet (1 m) at confluence of the Neches River and Pine Island Bayou. Northern regions are characterized by low gently rolling hills and well-formed drainage systems of streams and creeks in the landscape. The southern regions are comparatively flat, with poor drainage and support moderately extensive wetlands.[11][17]

Hydrology: Hardin, Tyler, western Jasper and southeast Polk counties are drained by the Neches River and its tributaries: Village Creek and its smaller tributaries (Beach, Theuvenins, Turkey, Hickory, Kimball, Big Sandy, and Cypress creeks) in the north; Pine Island Bayou and its smaller tributaries (Little Pine Island Bayou and Mayhaw Bayou) in the south. Eastern regions, including eastern Jasper and Newton counties, are drained by several relatively short creeks running into the Sabine River. Western regions including central Liberty, northeastern San Jacinto, northern Walker counties and southwest Polk County (via Kickapoo, Long King, and Menard creeks) are drained by the Trinity River. Areas farther west are drained by the San Jacinto River, with east and west forks. Additional wetlands are extensive, including innumerable nameless swamps, cypress sloughs, oxbow lakes, wetland savannas, and baygall bogs. Floodplains and bottomlands in the south, can retain surface water for days and weeks after rain. The Sabine and Neches rivers flow into Sabine Lake, a natural occurring brackish water estuary, just southeast of the Big Thicket. The other large lakes in the region were constructed in the decades following the Second World War, including B.A. Steinhagen Lake (1947–53) and Sam Rayburn Reservoir (1956–65) on the Neches River drainage, Lake Livingston (1966–69) on the Trinity River, Lake Houston (1953) and Lake Conroe (1970–73) on the San Jacinto River.[6][11][18]

Climate: The proximity to the Gulf of Mexico gives the region a climate of mild winters, hot summers, and high humidity most of the year. Average precipitation is 55 inches (140 cm) a year,[19] with northern areas receiving about 50 inches (130 cm), and southern areas receiving about 60 inches (150 cm). However, tropical storms and hurricanes can increase annual rainfall to over 100 inches (250 cm). Humidity stays well above 60% most of the time and exceeds 90% often. Winters are mild, with nighttime lows averaging 38–48 °F (3–9 °C) and daytime highs 55–65 °F (13–18 °C). Winter cold fronts can drop temperatures to freezing, but freezes rarely last for more than a few days, sometimes only hours, averaging about 20 mostly nonconsecutive days each year. Snow is rare, occurring only once every ten years or so. Summer temperatures are hot, with nighttime lows averaging 69–72 °F (21–22 °C) and daytime highs averaging 89–94 °F (32–34 °C). Temperatures exceed 90 °F (32 °C) about 110 days each year and days with temperatures above 95 °F (35 °C) and even above 100 °F (38 °C) are not uncommon. The high summer temperatures with high humidity levels can produce very high heat index numbers.[6][11][20]

Population: In 2010, the United States Census Bureau reported a population of 54,635 for Hardin County, with an average of 61.3 inhabitants per square mile (23.7/km²) in a county of 890.5 square miles (2,306 km²). The larger towns (and populations from 2010 census) in Hardin County are Kountze, the county seat (2,123), Lumberton (12,448), Silsbee (6,611), and Sour Lake (1,813). Smaller unincorporated communities in the Hardin County include Batson, Honey Island, Saratoga, Thicket, Village Mills, and Votaw.[21]

Tyler County had a total population of 21,766, with an average population of 23.5 inhabitants per square mile (9.1/km²) in 924.5 square miles (2,394 km²). The larger towns in Tyler County are Chester (312), Colmesneil (596), Warren (757), and Woodville, the county seat (2,586) with smaller unincorporated communities including Doucette, Fred, Rockland, and Spurger.

Polk County had a total population of 45,413, with an average of 43 inhabitants per square mile (17/km²) in an area of 1,057.1 square miles (2,738 km²) in 2010 including Livingston (5,335), the county seat and the largest town in the county.[21]

Larger towns and cities in the greater region include Beaumont, Jefferson County, located at the southeast corner of the Big Thicket area with a population of 118,296 and Liberty, Liberty County (8,397), on the southern edge of the Big Thicket area. Houston, Harris County, with a population of 2,320,268 (greater metropolitan area over 7,000,000) is one of the largest metropolitan areas in the US with its central, downtown area located 75 miles (121 km) by air southwest of the town of Kountze, Hardin County.[21]

Economy: Timber, oil and gas, and agriculture continue to be significant to the economy of the area. Many people commute to work in oil refineries and related industries in the Beaumont area. Other sources list industries providing significant employment in Hardin County as: educational, health and social services, construction, recreation, accommodation and food services, finance, insurance, real estate, and rental and leasing.[21][22]

On a larger scale of ecoregions of the United States, the Big Thicket is part of the Piney Woods.[23] The Big Thicket is located in the southwest of the Piney Woods and transitions into the Western Gulf coastal grasslands[24] immediately to the south. To the west are the Texas Blackland Prairies and East Central Texas forests[25] (a.k.a. post-oak savanna). Within the Big Thicket, a major component in the high diversity of plants and animals is the variety of ecosystems present in a relatively small area. The National Park Service identifies eight plant communities in Big Thicket National Preserve.[26] Some biologist and plant ecologists identify as many as nine, ten, or eleven ecosystems in the Big Thicket.[5][6][11] In nature these ecosystems are not always found in pure, large tracts of land, and often occur in intertwined and checkerboard mixes and ecotones, transitioning into one another. Ecosystems do not have universal standardized names. Many ecologist, botanist, zoologist and others have studied and classified ecosystems in the Big Thicket region (and elsewhere), defining and naming these communities as relevant to their own disciplines and studies.[27][5] Although the exact names, definitions, and boundaries might vary (subdivided, compounded, or overlapping), below are summaries of ten major ecosystems recognized by most who have studied and written about the Big Thicket, starting with higher elevations in the north, and in a generalized way, moving to lower elevations in the south.

Longleaf pine upland habitat. Big Thicket National Preserve, Turkey Creek Unit, Tyler Co. Texas; 1 May 2020

Uplands (aka: longleaf pine-bluestem uplands;[6] dry upland forests;[28][27] longleaf pine uplands[5][11]): In its natural state, this ecosystem is often described as having a park-like appearance, with widely spaced pine and oak trees, and grasses growing in the partially shaded open areas. Longleaf pine-bluestem grass uplands are most extensive in northern areas, on higher elevation plateaus between streams and dry upper slopes, where the soils of the Catahoula, Fleming, Willis, and Bentley formations often have several feet of moderately coarse sand over an iron oxide clay or plinthite hardpan stratum. The permeable sands and topography provide good drainage in the uplands which are relatively dry. Smaller fragments of this type are also found throughout the south where higher ridges, hills, and knolls occur. Longleaf pine (Pinus palustris) is a common species in this ecosystem and one of the dominant trees along with shortleaf pine (Pinus echinata) and a variety of oaks (Quercus). Understory shrubs include flowering dogwood (Cornus florida) and American holly (Ilex opaca). Plant ecologist Geraldine Watson stated the U.S. Forest Service grass herbarium in Louisiana has over 200 species of grasses from this range and various bluestem grasses (Andropogon) are the dominant ground cover.[11] Wildflowers like purple pleat-leaf (Alophia drummondii) and bird-foot violet (Viola pedata) grow in the lighter, semi-shaded areas, while Texas Dutchman's-pipe (Aristolochia reticulata) and false foxglove (Aureolaria grandiflora) grow in the deeper shade. Streams flowing through these areas can support large stands of southern bracken fern (Pteridium aquilinum). Longleaf pine, bluestem grass, and many other plants in these areas are pyrophytic (adapted and resistant to wildfire), and wildfires are a critical factor in maintaining this ecosystem. Historically, naturally occurring fires would periodically eliminate non-pyrophytic plant species encroaching on this plant community. However, decades of fire suppression has allowed a wide mixture of species to invade and in time has turned many of the upland localities into beech-magnolia-loblolly slope forest or oak-hickory forest. Additionally, many areas clearcut for lumber have been replanted with rows of the faster growing, non-native slash pine (Pinus elliottii) eliminating much of the longleaf pine-bluestem grass uplands from Texas.[6][11][27]

Arid sandyland habitat with longleaf pine trees (Pinus palustris) and Louisiana yucca (Yucca louisianensis) growing among the sparse groundcover. Roy E. Larsen Sandyland Sanctuary, Hardin Co. Texas, USA; 6 November 2019

Sandylands (aka: arid oak-farkleberry sandylands;[6] sand ridge savanna;[28] sandhill pine forests;[27] arid sandylands[5][11]): Sandylands resemble and have much in common with upland forest, with open grassy areas and widely spaced trees. However, the fundamental difference lies in the soils. These areas reside on deep sand dunes deposited by ancient seas and rivers. In contrast to the uplands where a few feet of coarse sand sits on a hardpan stratum, sandylands sit on layers of fine sand with thin layers of silicious silt that can be over a hundred feet deep, with little clay and low fertility. Although these areas receive the same rainfall as the rest of the region, water drains quickly in the deep sand which dries in the sun leaving an arid surface. The ground cover can be meager in places with sparse grasses, lichen, or even exposed sand in some spots. Plants adapted to arid environments like Louisiana yucca (Yucca louisianensis) and prairie prickly pear (Opuntia macrorhiza) are conspicuous indicators of sandylands in the humid Big Thicket climate. Although found throughout the region, some of the largest and best examples are in the vicinity of the Neches River and Village Creek. In the more arid sites bluejack oak (Quercus incana), sand post oak (Quercus margaretta), north blackjack oak (Quercus marilandica), post oak (Quercus stellata), black hickory (Carya texana), and mockernut hickory (Carya tomentosa) are dominant hardwoods. With increasing moisture levels longleaf pine (Pinus palustris) and loblolly pine (Pinus taeda) emerge over the oaks. Longleaf pine is characteristic of sandylands, but not always dominant. Farkleberry (Vaccinium arboreum) is the dominant shrub in the understory. Several rare wildflowers with limited distributions in Texas can be found in this environment; examples include Oklahoma prairie clover (Petalostemum griseum), Carolina vervain (Stylodon carneus = Verbena carnea), Hooker palafoxia (Palafoxia hookeriana), green-thread (Thelesperma flavodiscum), and trailing phlox (Phlox nivalis texensis) which is also an endangered species. Like the uplands, periodic wildfires are essential to keeping the understory open and preserving this ecosystem. These areas are said to have been preferred habitation sites for the nomadic Atakapa-Ishak people in Pre-Columbian times.[6][11][27]

Pine savannah wetland habitat with pitcher plants (Sarracenia alata). Big Thicket National Preserve, Turkey Creek Unit, Tyler Co. Texas; 1 May 2020

Savannas (aka: longleaf - black gum savannahs;[6] wetland longleaf pine savannas;[28] wetland pine savannas;[27] pine savannah wetlands[5][11]): If the sandylands described above resemble a well drained and arid version of the uplands, the savanna wetlands might be described as a poorly drained, wet version. This ecosystem is characterized by the same open spaces with widely spaced pine trees as uplands and sandylands, but differs in being very flat, with a relatively thin layer of low nutrient, fine, packed sand, sitting on hardpan which is very near the surface. The nearly impervious hardpan both inhibits drainage in wet periods as well as prevents moisture from rising in dry periods. The severity of the fluctuating water table, along with occasional low-intensity ground fires that are necessary to sustain this ecosystem, limit the plants that can grow there. Savanna wetlands are most often found to the south of the uplands, on the Montgomery and recent Bentley formations, although they are not entirely restricted to this zone. Longleaf pine (Pinus palustris) along with black gum (Nyssa sylvatica), often stunted, make up much of the overstory, being among the few trees that grow in the severe conditions. Ground cover is dominated by rushes, sedges (Rhynchospora and Scleria), and grasses including Andropogon, Aristida, Muhlenbergia, and little bluestem (Schizachyrium scoparium). Within the flat savannas, the slightest change in elevation can produce significantly different vegetation. Occasional mounds with two or three feet of sand, support upland habitat, while depressions of just a few inches can hold acid bogs, with low pH levels and low levels of nutrients such as nitrogen, potassium, phosphorus, and calcium. Even the peripheral areas around acid bogs, distinguished by subtle sloping elevations of only an inch or two, sustain a distinct zone of vegetation. Sphagnum mosses and carnivorous plants are adapted to these environments, including the pitcher plant (Sarracenia alata), annual sundew (Drosera brevifolia), rush bladderwort (Utricularia juncea), and small butterwort (Pinguicula pumila). A number of orchids are found in savannas including the grass pink orchid (Calopogon tuberosus), yellow fringed orchid (Platanthera ciliaris), snowy orchid (Platanthera nivea), and snake mouth orchid (Pogonia ophioglossoides).[6][11][27]

Slope forest with a blackwater stream flowing through mixed deciduous and evergreen woodlands. Big Thicket National Preserve, Big Sandy Creek Unit, Polk Co. Texas; 23 Mar 2020

Slope forests (aka: beech-magnolia-loblolly slopes;[6] mesic upland forests: lower slope hardwood pine forest;[27] beech-magnolia-loblolly pine association[5][11]): Slope forest have a wide mix of conifers, deciduous, and evergreen broad-leaved trees occupying the gentle slopes between the wet bottomlands and the dryer uplands. Small spring-fed streams drain the slopes before reaching the larger creeks. The closed canopy filters the light reaching the forest floor where an ample layer of leaf litter holds water, creating a mesic understory. The soils are relatively fertile with fine, loamy, sands and are well to moderately drained. The purest examples of slope forest are found on the soils of the Willis Formation with red clay in Jasper, Newton, Polk, and Tyler counties, but they extend well into the lower, southern regions where soils and topography are suitable, particularly along the slopes of the waterways. A variety of trees co-dominate slope forest and these can vary with elevation and moisture. In higher and less humid areas, forest shortleaf pine (Pinus echinata), loblolly pine (Pinus taeda), white oak (Quercus alba), and southern red oak (Quercus falcata) co-dominate, but sweetgum (Liquidambar styraciflua) and blackgum (Nyssa sylvatica) are also common. More humid areas tend to shift to American beech (Fagus grandifolia), southern magnolia (Magnolia grandiflora), and American holly (Ilex opaca) co-dominating with loblolly pine (Pinus taeda), but include 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.[6][11][27]

Floodplains are dominated by hardwood trees and pine trees are uncommon or absent. Big Thicket National Preserve, Big Sandy Creek Unit, Polk Co. Texas, USA; 12 May 2020

Floodplains (aka: sweet gum - oak floodplains;[6] wet forests: floodplain hardwood forest;[27] oak-gum floodplain;[5] stream floodplains[11]): 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 hickory (Carya aquatica), and red maple (Acer rubrum), often with a dense mid-story of ironwood (Carpinus caroliniana). Among the many wildflowers are three irises, yellow iris (Iris pseudacorus), southern iris (Iris virginica), and short-stem iris (Iris brevicaulis), as well as the fragrant ladies tresses orchid (Spiranthes odorata), blue jasmine (Clematis crispa), and the aquatic spatterdock (Nuphar luteum). Although the floodplains in the region share much in common with one another, each river varies with some unique elements and plant species. The Trinity River basin in particular stands out in contrast to others with calcareous, relatively high pH, alkaline soils supporting vegetation that is seldom seen in other watersheds, including bois d'arc also called horse apple (Maclura pomifera), blueberry hawthorn (Crataegus brachyacantha), cedar elm (Ulmus crassifolia), and Texas sugarberry (Celtis laevigata).[6][11][27]

Baygall habitat in the Big Thicket National Preserve, Jack Gore Baygall Unit, Hardin Co. Texas, USA; 6 November 2019

Baygalls[6][27][5] (aka: bay-gallberry holly bogs in part;[6] Acid bog baygalls[11]): With dense undergrowth and twisted vines growing in stagnant, blackwater, acid bogs, under a shadowy canopy of swamp tupelo and cypress, baygalls are often said to exemplify and epitomize the Big Thicket. Baygalls typically form at the base of slopes where seeps, springs, and rainwater drain onto the margins of the flat floodplains and bottomlands, away from the main channels. The drainage from the slopes maintain saturated, muddy soils in these already damp and humid areas, where pools, bogs, and stagnant drainages form in depressions on the flat landscape. With sphagnum mosses and high peat content, baygall soils and water have very high acidity, pH levels of 4.5 are common. The high acid levels are a significant factor in distinguishing baygalls from the floodplain and flats ecosystems. Although baygall waters are generally shallow and torpid, they sometimes form small, highly acidic blackwater streams, slowly moving into the larger creeks and bayous. Hanging bogs occur where water pools on irregular flat and low areas on the slopes above the bottomlands. The name baygall is derived from sweetbay magnolia (Magnolia virginiana) and sweet gallberry holly (Ilex coriacea). These and swamp titi (Cyrilla racemiflora) are dominant and other common shrubs include southern bayberry (Myrica cerifera), water willow (Decodon verticillatus), red bay (Persea borbonia), and Virginia sweetspire (Itea virginica). Vines like muscadine grape (Vitis rotundifolia), supplejack or rattan-vine (Berchemia scandens) can grow impressively large. Larger trees include swamp tupelo (Nyssa biflora) and bald cypress (Taxodium distichum). In addition to the prominent fragrant water-lily (Nymphaea odorata), baygalls harbor many small and obscure wildflowers such as four species of carnivorous bladderworts (Utricularia), and saprophytic species like burmannia (Burmannia biflora) and nodding-nixie (Apteria aphylla). Some baygalls and hanging bogs are no more than a small pool, while others can be a mile across. One author[5] states that the Jack Gore Baygall Unit of the BTNP, at 12 square miles, is the largest baygall in the world.[5][6][11][27]

Palmetto-oak and hardwood flats habitat with dwarf palmettos (Sabal minor) and resurrection fern (Pleopeltis polypodioides) growing on tree limb at the top of photo. Big Thicket National Preserve, Lance Rosier Unit, Hardin Co. Texas, USA: 23 October 2019

Flats (aka: palmetto-oak flats;[6] wet forests;[27] palmetto-hardwood flats[5][11]): Dense stands of dwarf palmettos (Sabal minor) are an indicator of this ecosystem and it can have an exotic and tropical look with epiphytes draping from the trees, like Spanish moss (Tillandsia usneoides) and resurrection fern (Pleopeltis polypodioides). Some of the most extensive and well preserved palmetto-oak flats are found around Pine Island Bayou and Little Pine Island Bayou, the area known as the "Traditional Thicket" or "Hunter's Thicket". Flats, often several miles wide, are old river channels and floodplains and their associated bars and levees, filled with centuries of sediments and alluvium deposits. They are some of the flattest and lowest areas in the Big Thicket. Flats are typically poorly drained areas with very deep calcareous soils of a high clay content having vertisols properties, meaning the soil moves, shrinking and swelling with moisture content. Palmetto-oak flats alternate between flooded and dry conditions, with a few inches of water standing for days, weeks, even months after rains, to dry periods in which the soils dry, leaving large and deep cracks in the hard baked surface. The canopy is made up of several hardwoods species of which the swamp chestnut oak or basket oak (Quercus michauxii), laurel oak (Quercus laurifolia), overcup oak (Quercus lyrata), swamp post oak (Quercus similis), and cedar elm (Ulmus crassifolia) are dominant species. Other trees and shrubs filling in the canopy and understory include sweetgum (Liquidambar styraciflua), Carolina ash (Fraxinus caroliniana), blueberry hawthorn (Crataegus brachiacanthua), and arrowwood viburnum (Viburnum dentatum). The shade of the canopy and the severity of the wet and dry conditions limit the species that grow in the understory. However the dwarf palmetto (Sabal minor) thrives, typically growing to about 4 feet (1.2 m), although occasional specimens can be found up to 10 to 15 feet (3.0 to 4.6 m) tall. Some regard the larger specimens as a different species or variety, the Louisiana palmetto (Sabal louisiana), others do not recognize it a valid species. Other understory species found on the flats are creeping spot-flower (Spilanthes americana), Missouri ironweed (Vernonia missurica), lance-leaved water-willow (Justicia lanceolata), and inland sea oats (Chasmanthium latifolium). The ancient levees and bars deposited along the old river channels, varying in size from less than an acre up to 10 acres (4.0 ha), are slightly higher with better drainage supporting stands of loblolly pine (Pinus taeda) and water oak (Quercus nigra) with understory species such as Hooker eryngo (Eryngium hookeri), and sharp-sepal penstemon (Penstemon tenuis). Bald cypress (Taxodium distichum) and water tupelo (Nyssa aquatica) grow in and near permanent or semi permanent water and the disc water-hyssop (Bacopa rotundifolia) may be found floating or growing at the water's edge. Drainage patterns are significant in shaping and maintaining these ecosystems and drainage alterations have reduced the historical size of this community.[5][6][11][29]

Cypress slough habitat. Big Thicket National Preserve, Turkey Creek Unit, Hardin Co. Texas; 16 April 2020

Cypress slough[5] (aka: sweet gum - oak floodplains in part;[6] swamp-cypress tupelo forest;[27] slough, oxbows, and cypress-tupelo swamps[11]): Recognized as a distinct ecosystem by some, regarded as a component found within the flats, floodplains, and baygall bogs by others, cypress sloughs with older bald cypress (Taxodium distichum) and their buttresses and protruding knees are impressive environments. Cypress sloughs occupy low laying areas in the floodplains of creeks and rivers set back from the main channels, with still or very slow moving permanent, or semi permanent, water, like secondary channels, ox-bow lakes, sloughs, and ponds. Cypress sloughs are found throughout the region but, are perhaps more extensive in the low laying south. The dominant trees are the bald cypress (Taxodium distichum) and the water tupelo (Nyssa aquatica). Water tupelo often grow in deeper water and bald cypress in shallower parts or at the periphery, although both are adapted to growing in permanently submerged areas or on dry land with sufficient moisture. Understory trees and shrubs found growing around cypress sloughs include water or Carolina ash (Fraxinus caroliniana), water elm (Planera aquatica), river birch (Betula nigra), eastern hop-hornbean (Ostrya virginiana), and buttonbush (Cephalanthus occidentalis). Plants like lizard's tail (Saururus cernuus) and burhead (Echinodorus cordifolius) can be seen growing in shallow water with cardinal flower (Lobelia cardinalis) and sensitive fern (Onoclea sensibilis) at the water's edge. Bald cypress trees typically live for 600 years or more and some are known to have lived 1,200 years. Cypress is a valuable hardwood, particularly prized for its resistance to rot and highly valued for shipbuilding, docks, and bridges. Consequently, this ancient swamp forest, once common in the region, have been greatly reduced because of logging in the nineteenth century. Trees over 100 years old are rare in the area now.[5][6][11][27][30]

Marysee Prairie Preserve in the Big Thicket region of southeast Texas. Liberty Co. Texas; 22 May 2020

Mixed-grass prairies:[6][5][11] Prairies (small patches are sometimes called coves), are sometimes included as a Big Thicket ecosystem. These are isolated fragments of coastal prairie more typical of Chambers and Jefferson counties to the south, in areas mostly found where the forest and coastal prairies transition. Prairies are dominated by grasses and herbaceous plants, some are the same as those found longleaf pine savannas, but others are distinctive like Indian grass (Sorghastrum nutans) and prairie bluebell (Eustoma grandiflorum). Common grasses of these areas include Indian grass (Sorghastrum avenaceum), eastern gama-grass (Tripsacum dactyloides), and tall dropseed (Sporobolus asper). One author distinguished prairies from longleaf pine savannas by the presence of pimple mounds or mima mounds. Prairies and coves were once found in the Big Thicket with some consistency, particularly in higher elevations in the south, and specifically in higher southwestern areas between the Pine Island Bayou and the Trinity River drainages. However, natural wildfires are an important factor in maintaining these areas and when fire is suppressed, trees and shrubs quickly grow in and fill in these areas. The Chinese tallow tree (Triadica sebifera) is a particularly aggressive and problematic invasive species in prairie habitat in the region. Prairies are also often the first areas to be developed for farming and residential housing. Unfortunately, prairies in the Big Thicket are now rare.[5][6][11]

Texas State Highway 1276 in the Big Thicket National Preserve, Big Sandy Creek Unit, Polk County, Texas; 12 May 2020

Roadsides[6][5] and river edge: Although not a natural or even stable plant assemblage, some have recognized roadsides as an ecosystem in the Big Thicket. Proponents of the concept have identified a number of distinguishing characteristics of roadsides from the other ecosystems. Sunlight and heat can reach the ground along the clear highway easements, unlike most areas where the light is filtered by the forest canopy before it reaches the ground. Roadsides receive more rainwater, diverted from the pavement and often retained for a time in roadside ditches. Soil types not normally found at the surface are often exposed with the construction of roads, particularly deep road cuts in the low hills in the north that expose calcareous soils or where the formations are thin near transition zones supporting the growth of plants not normally occurring in the surrounding habitat, allowing for more diverse plants species to grow. The "corridor effect"[6] of traffic, both human (vehicles, tourists, and road crews) and birds and other animals, inadvertently dispersing seeds and roots along roadsides from other areas. And finally, regular cycles of mowing and cutting, as well as the use of herbicides can both inhibit and benefit various wildflowers and plant species growing there. Most plant species at any given roadside represent the association immediately adjacent to that locality, but often have a few odd of species from other areas. Roadsides are a convenient and accessible places to view wildflowers, regardless of whether they are true ecosystems. In the past some (including the National Park Service) have discussed the river edge as an ecosystem in the Big Thicket however, most ecologist do not recognize river edges as an ecosystem distinct from the one a river runs through.[5][6]

• Big Thicket gallery
• 
  Longleaf pine (Pinus palustris) upland habitat after a recent fire. Big Thicket National Preserve, Hickory Creek Unit, Tyler Co. Texas; 23 Mar 2020
• 
  The same vicinity as previous image five months after the fire. Big Thicket National Preserve, Hickory Creek Savannah Unit, Tyler Co. Texas; 20 Aug 2020
• 
  Sphagnum bogs or "acid bogs" with pH levels as low as 4.5 occur in the region. Big Thicket National Preserve, Turkey Creek Unit, Tyler Co. Texas; 1 May 2020
• 
  Baygall blackwater (left) mixing with typical muddy water (right). Big Thicket National Preserve, Jack Gore Baygall Unit, Hardin Co. Texas; 3 April 2020
• 
  Lush vegetation in the Village Creek floodplain. Roy E. Larsen Sandyland Sanctuary, Hardin Co. Texas; 30 April 2010

Exact numbers of plant and animal species occurring in the Big Thicket region are difficult to state objectively due to a number of factors including: the imprecise boundaries of the area; which (if any) accidental and vagrant species to count; whether to count extinct and extirpated species; whether to count introduced and invasive species; migratory vs. resident species; frequent taxonomic changes and taxonomic instability. These and other factors all contribute to what sometimes appear as inconsistent or contradictory counts and numbers.

The area contains over 100 species of trees and shrubs, with longleaf pine (Pinus palustris) once dominating the region. Big Thicket National Preserve has introduced programs to re-establish this dominance, including one of the US's most active prescribed burn programs. With the National Park Service's centennial occurring in 2016, efforts were made to plant between 100,000 and 300,000 longleaf pines. The National Park Service lists more than one thousand species of flowering plants and ferns that can also be found in the thicket, including 20 orchids and four types of carnivorous plants.

• Wildflower gallery
• 
  Coral bean (Erythrina herbacea) Tyler County
• 
  False gromwell (Onosmodium bejariense) Walker County
• 
  Rose mallow (Hibiscus sp.) Hardin County
• 
  Pinewoods lily (Alophia drummondii) Hardin County
• 
  Turkcap (Malvaviscus arboreus var. drummondii) San Jacinto County
• 
  Ladies'-tresses orchid (Spiranthes sp.) Tyler County
• 
  Turnsole (Heliotropium indicum) Liberty County

• 
  Southern arrowwood (Viburnum dentatum), Tyler County
• 
  Broad-leaf snoutbean (Rhynchosia latifolia), Polk County
• 
  Grass-pink orchid (Calopogon sp.), Tyler County
• 
  Pitcher plant (Sarracenia alata), Tyler County
• 
  Butterfly pea (Centrosema virginianum), Polk County
• 
  Lance-leaved coreopsis (Coreopsis lanceolata), Hardin County
• 
  Short-stem iris (Iris brevicaulis) Polk County

During the last glacial period, plant and animal species from many different biomes moved into the area. Before their extinction, the Big Thicket was home to most species of North American megafauna.

Well over 500 species of vertebrates occur in the Big Thicket region, including more than 50 mammals, 300 birds, 60 reptiles, 30 amphibians, and over 90 fishes. The records and numbers below for mammals, reptiles, and amphibians are based on county records for Hardin, Jasper, Liberty, Montgomery, Polk, San Jacinto, Tyler, and Walker counties, which in a few cases may reflect marginal, peripheral, and vagrant records for a given species in the region and not all of the species are ubiquitous or evenly distributed throughout the Big Thicket.[31][32]

Mammals: About 54 species of mammals occur in the Big Thicket (not counting extirpated species), including such species as the Virginia opossum (Didelphis virginiana), nine-banded armadillo (Dasypus novemcinctus), short-tailed shrew (Blarina carolinensis), American beaver (Castor canadensis), Baird's pocket gopher (Geomys breviceps), southern flying squirrel (Glaucomys volans), white-tailed deer (Odocoileus virginianus), eastern spotted skunk (Spilogale putorius), American mink (Mustela vison), river otter (Lontra canadensis), coyote (Canis latrans), gray fox (Urocyon cinereoargenteus), bobcat (Lynx rufus), and Rafinesque's big-eared bat (Corynorhinus rafinesquii) a threatened species in Texas.[33] Although many of these species are common, they can be highly secretive and are seldom seen in the dense woodlands. Many prominent species that once occurred in the Big Thicket have been extirpated from their historical ranges. Examples include hog-nosed skunks (Conepatus leuconotus), red wolves (Canis rufus), ocelots (Leopardus pardalis), and jaguars (Panthera onca).[31] In 1902 ornithologist Harry Church Oberholser reported what he considered reliable accounts of jaguars in east Texas, including one killed south of Jasper a few years earlier, along the Neches River near Beaumont, and in the timber south of Conroe.[31]

Although once common in the Big Thicket, the American black bears (Ursus americanus) was the target of a concerted effort to extirpate them from east Texas in the late nineteenth century. Reports of field naturalists in 1902 indicated:

• Conroe: "A few still found in the big thicket 15 mile south of here."
• Beaumont: "A few still found in the forest northwest of here."
• Sour Lake: "Still common in the swamps near here; a few killed every year."
• Rockland: "Now very rare or quite extinct."

Vernon Bailey, chief naturalist for the U.S. Biological Survey, interviewed a hog farmer and bear hunter named Ab Carter in 1904. Carter reported that in 1883, he and a neighbor set out to exterminate the bears in the Tarkington Prairie area of Liberty County that preyed on their free ranging hogs in the forest. That same year 182 bears were killed within a 10-mile (16 km) radius of Tarkington Prairie and annual hunting continued until 1900 when the last two bears were killed in that area. Currently, extremely rare bear sightings in east Texas are believed to be wandering individuals from reintroduction efforts in adjacent areas of Louisiana. They are now a threatened species in Texas[33] and the National Park Service list them as "probably present".[7][31]

Conversely other species have been introduced to the area like the nutria (Myocastor coypus) from South America, now common in the area. Feral pigs (Sus scrofa) "constitute one of the most serious conservation threats in Texas."[31] They prey on natural populations of invertebrates, amphibians, reptiles, ground nesting birds, and rodents and are known to play a role in the transmission of disease including brucellosis, pseudorabies, and swine fever. Their forging habits involve rooting up and disturbing soils, reducing both the numbers of individual plants and animals and the number species in any given area.[31]

• Mammal gallery
• 
  Nine-banded armadillo (Dasypus novemcinctus)
• 
  American beaver (Castor canadensis)
• 
  Southern flying squirrel (Glaucomys volans)
• 
  Rafinesque's big-eared bats (Corynorhinus rafinesquii)
• 
  Eastern spotted skunk (Spilogale putorius)
• 
  River otter (Lontra canadensis)
• 
  Bobcat (Lynx rufus)

Birds: Three hundred species of migratory and nesting birds occur in the Big Thicket including the red-cockaded woodpecker, a state and federal endangered species.[33] The extinct ivory-billed woodpecker once occurred in the Big Thicket.[34]

• Bird gallery
• 
  Red-cockaded woodpecker
• 
  Bachman's sparrow (Peucaea aestivalis), Hal Scott Reserve, Florida
• 
  Scissor-tailed flycatcher (Tyrannus forficatus) in Walker County
• 
  Painted bunting (Passerina ciris), Texas
• 
  Yellow-crowned night-heron (Nyctanassa violacea) in Harris County
• 
  White ibis (Eudocimus albus) adult and immature plumage, Trinity River National Wildlife Refuge

Reptiles: Sixty-one species of reptiles are known from the Big Thicket area including the alligator, 15 turtles, 12 lizards, and 33 snakes. Along with birds, reptiles are among the more commonly seen wildlife and they are an important part of the forest community or ecosystems. The American alligator (Alligator mississippiensis), although somewhat uncommon, occurs throughout the Big Thicket where sufficient water is found. However, alligators are abundant in the open marshland of Chambers and Jefferson counties to the south, where they bask in the sun unobstructed by forest trees.[32]

Turtle diversity in the American Gulf Coast states is among the highest in the world. The red-eared slider (Trachemys scripta) is the most common of the pond and river turtles, although river cooters (Pseudemys concinna), Mississippi map turtles (Graptemys pseudogeographica), Sabine map turtles (Graptemys sabinensis), and the rare chicken turtle (Deirochelys reticularia) all occur there. The worldwide distribution of the Sabine map turtle is limited to the Sabine and Neches rivers and adjacent drainages of southwest Louisiana. The once ubiquitous and abundant three-toed box turtle (Terrapene carolina) is still occasionally encountered in east Texas but its numbers plummeted in the late twentieth century, while the ornate box turtle (Terrapene ornata), at its eastern range limits, is known from a few county records in the area, as is the yellow mud turtle (Kinosternon flavescens). The Mississippi mud turtle (Kinosternon subrubrum), razorback musk turtle (Sternotherus carinatus), and common musk turtle (Sternotherus odoratus) spend much or their time foraging at the bottom of the murky waters but, occasionally can be seen basking or even on land moving between streams and ponds. Powerful swimmers, the largely aquatic spiny soft-shelled turtle (Apalone spinifera) is found throughout the region, while the smooth soft-shelled turtle (Apalone mutica) prefers the larger rivers, creeks, and bayous.[32][35] The snapping turtle family (Chelydridae) is found only in the New World with two genera, both represented in the Big Thicket, the common snapping turtle (Chelydra serpentina) and the alligator snapping turtle (Macrochelys temminckii). The alligator snapping turtle is the largest freshwater turtle in North America and one of the larger freshwater turtles in the world. One record sized individual with a 31.5-inch (80 cm) shell has been documented, and another 251-pound (114 kg) captive specimen recorded, however, 35–100 pounds (16–45 kg) and 12–20 inches (30–51 cm) is the typical adult size.[35] Alligator snapping turtles are protected as a threatened species in Texas.[33]

Lizards commonly seen include green anoles (Anolis carolinensis), five-lined skinks (Plestiodon fasciatus), broad-headed skinks (Plestiodon laticeps), ground skinks (Scincella lateralis), and prairie lizards (Sceloporus consobrinus). Six-lined race runners (Aspidoscelis sexlineatus) are not uncommon, but limited to open areas with sandy soils,[36] whereas the legless western slender glass lizard (Ophisaurus attenuatus) prefers areas of dense grasses with sandy soils. Three lizards barely range into peripheral counties, including two rare skinks, the southern prairie skink (Plestiodon septentrionalis) in the west and the coal skink (Plestiodon anthracinus) in the northeast; and the Texas spiny lizard (Sceloporus olivaceus), common to the west, but rare in a few western Big Thicket counties. Most records of the state reptile, the Texas horned lizard (Phrynosoma cornutum), from east Texas are from the early and mid-twentieth century when they were popular pets, and are thought to represent released or escaped pets and not the species natural range.[37] Two invasive species, the brown anole (Anolis sagrei) and the nocturnal Mediterranean gecko (Hemidactylus turcicus), are found there.[32]

• Reptile gallery
• 
  American alligator (Alligator mississippiensis) in Chambers County
• 
  Razorback musk turtle (Sternotherus carinatus) in Hardin County
• 
  Sabine map turtle (Graptemys sabinensis) in Orange County
• 
  Three-toed box turtle (Terrapene carolina) in Walker County
• 
  Five-lined skink (Plestiodon fasciatus) in Liberty County
• 
  Prairie lizard (Sceloporus consobrinus) in Hardin County
• 
  Green anole (Anolis carolinensis) in Polk County

Snakes: With 33 species, the highest diversity among the reptiles are the snakes. Some of the more common species include the eastern hognose snake (Heterodon platirhinos), brown snake (Storeria dekayi), western ribbon snake (Thamnophis proximus), and the rough greensnake (Opheodrys aestivus). Two large, common, but harmless species, the coachwhip snake (Masticophis flagellum) and the Texas rat snake (Pantherophis obsoletus), both commonly grow to 42 inches (110 cm); 60-inch (150 cm) individuals are not rare, and they occasionally grow even larger. The North American racer (Coluber constrictor) occurs in three color variations in the Big Thicket, some recognize them as subspecies, the buttermilk racer (C. c. anthicus), the yellow-bellied racer (C. c. flaviventris), and the tan racer (C. c. etheridgei). The harmless watersnakes bear a resemblance and share habitats with venomous cottonmouths, including three common species, the yellow-bellied watersnake (Nerodia erythrogaster), southern or broad-banded watersnake (Nerodia fasciata), diamondback watersnake (Nerodia rhombifer), and the uncommon Mississippi green watersnake (Nerodia cyclopion). Some less common species that are occasionally encountered are the western mud snake (Farancia abacura), prairie kingsnake (Lampropeltis calligaster), speckled kingsnake (Lampropeltis holbrooki), Louisiana milk snake (Lampropeltis triangulum), and Slowinski's cornsnake (Pantherophis slowinskii). The rare and endangered Louisiana pine snake (Pituophis ruthveni) is known form historical records in the Big Thicket but might be extirpated from the area now. The Louisiana pine snake is closely associated with the Baird's pocket gopher (Geomys breviceps), both for prey and its burrows for shelter, and both species occupy longleaf pine uplands, savanna, and sandyland, habitat which is dependent on periodic cycles of wildfires to maintain an open understory.[33][32][38][39]

There are five species of venomous snakes in the area. Two rattlesnakes, the pygmy rattlesnake (Sistrurus miliarius) and the canebrake or timber rattlesnake (Crotalus horridus) are both uncommon to rare. Timber rattlesnakes are a threatened species in Texas, as they are in most states where they occur and are protected by state laws.[33] The Texas coral snake (Micrurus tener) is not uncommon however, they are secretive, often fossorial, and seldom seen. Two of the most common snakes, venomous or non-venomous, are the copperhead (Agkistrodon contortrix) and cottonmouth (Agkistrodon piscivorus). Venomous snakes deserve caution and respect, but are safely observed when distances of 15–20 feet are maintained.[32][39]

• Snake gallery
• 
  Diamondback watersnake (Nerodia rhombifer) in San Jacinto County
• 
  Rough greensnake (Opheodrys aestivus) in Tyler County
• 
  Texas rat snake (Pantherophis obsoletus) in Liberty County
• 
  Prairie kingsnake (Lampropeltis calligaster) in Tyler County
• 
  Texas coral snake (Micrurus tener) in Houston County
• 
  Copperhead (Agkistrodon contortrix) in Liberty County
• 
  Cottonmouth (Agkistrodon piscivorus) in Liberty County

Amphibians: There are 31 species of amphibians found in the Big Thicket area, including 11 species of salamanders and 20 species of frogs and toads.[32] Some of the more commonly encountered salamanders in the region include the smallmouth salamander (Ambystoma texanum), dwarf salamander (Eurycea quadridigitata), and central newt (Notophthalmus viridescens). The three-toed amphiuma (Amphiuma tridactylum) is one of the larger salamanders in the world and can grow over 30 inches (76 cm). Three salamanders, including the three-toed amphiuma (Amphiuma tridactylum), Gulf Coast water dog (Necturus beyeri), and lesser siren (Siren intermedia), retain their gills from the larva stage and live their entire lives in the muddy waters of east Texas and consequently, although not rare, are seldom seen except by an occasional fisherman or those who specifically go look for them. Likewise, mole salamanders (members of the genus Ambystoma), including the spotted salamander (Ambystoma maculatum), marbled salamander (Ambystoma opacum), mole salamander (Ambystoma talpoideum), and tiger salamander (Ambystoma tigrinum) spend much of their lives underground and are infrequently seen except for few short weeks each year during their breeding seasons. The southern dusky salamander (Desmognathus auriculatus), once widespread in Southeast Texas, now appears to be in serious decline.[32][40]

Common toads and frogs include the Gulf Coast toad (Incilius nebulifer), Blanchard's cricket frog (Acris blanchardi), green tree frog (Hyla cinerea), squirrel tree frog (Hyla squirella), spring peeper (Pseudacris crucifer), eastern narrow-mouth toad (Gastrophryne carolinensis), American bullfrog (Lithobates catesbeianus), bronze frog (Lithobates clamitans), and southern leopard frog (Lithobates sphenocephalus). Two other frequently encountered tree frogs, Cope's gray tree frog (Hyla chrysoscelis) and the gray tree frog (Hyla versicolor), are identical in appearance and can only be distinguished by subtle differences in their calls or by laboratory analysis. The East Texas toad, commonly seen in the Big Thicket, has been controversial among herpetologist and taxonomist, some arguing that it is a distinct species (Anaxyrus velatus) while others argue that it is a hybrid between Woodhouse's toad (Anaxyrus woodhousii) found to the west and Fowler's toad (Anaxyrus fowleri) found to the east. Two rare and highly secretive frogs are the pickerel frog (Lithobates palustris) and the southern crawfish frog (Lithobates areolatus) which is a fossorial species, spending much of its time in crayfish burrows and other small cavities in the ground. One invasive species, the small Rio Grande chirping frog (Syrrhophus cystignathoides), is native to the Rio Grande Valley and Mexico but, it does not appear pose an ecological threat to other species as invasive species often do.[32][41]

• Amphibian gallery
• 
  Small-mouthed salamander (Ambystoma texanum) in Liberty County
• 
  Dwarf salamander (Eurycea quadridigitata) in Polk County
• 
  Eastern newt (Notophthalmus viridescens) in Walker County
• 
  East Texas toad (Anaxyrus velatus or woodhousii × fowleri) in Hardin County
• 
  Eastern narrow-mouth toad, (Gastrophryne carolinensis) in Liberty County
• 
  Gray treefrog (Hyla versicolor) in Montgomery County
• 
  Green treefrog (Hyla cinerea) in Hardin County

Fishes: Well over 90 species of fishes are known from the area. The Big Thicket National Preserve inventoried 92 species in the preserve's waters and another 20 species are noted as possible occurrences.[42] The National Park Service checklist includes 104 species.[43] Others source note 98 species[5] and 94 species.[44] In the smaller tributaries the most abundant species are minnows, killifishes, darters, bass, and bullhead catfish, while larger creeks and bayous are dominated by channel, blue, and flathead catfish, sunfishes, largemouth and spotted bass, and crappie.[42]

Insects: Studies have documented nearly 1,800 species of Lepidoptera (butterflies and moths) in the Big Thicket.[45]

Dragonflies and damselflies (Odonata): Damselflies typically sit with their wings together, closed over their backs. Dragonflies sit with their wings spread. Collectively over 120 species occur in the Big Thicket area. They are often associated with water where they lay their eggs. Most species have preferences in the water they frequent, such as moving water vs. still water, streams, ponds, marshes etc. The Needham's skimmer (Libellula needhami) lay their eggs in flight, while the ebony jewelwing (Calopteryx maculata) submerges for up to two hours while depositing eggs. The nymphs are aquatic. Both the larva and adults are fierce predators, feeding primarily on insects. They are frequently sexually dimorphic and males and females may have different colors and patterns. Some species like the roseate skimmer (Orthemis ferruginea) and common green darner (Anax junius) can be seen in their adult form year round. Others are limited to a few weeks or mouths each year like the calico pennant (Celithemis elisa) flying April - August and Needham's skimmer (Libellula needhami) flying May - September. The Texas emerald (Somatochlora margarita) and the rare and sarracenia spiketail (Cordulegaster sarracenia) are endemic to southeast Texas and adjacent areas of Louisiana.[46][47]

• Dragonflies and damselflies (Odonata) gallery
• 
  Common green darner (Anax junius), male, Liberty County
• 
  Ebony jewelwing (Calopteryx maculata), male, San Jacinto County
• 
  Needham's skimmer (Libellula needhami) female, Harris Co County
• 
  Calico pennant (Celithemis elisa) male, Chambers County
• 
  Roseate skimmer (Orthemis ferruginea), male, Liberty County
• 
  Widow skimmer (Libellula luctuosa), female, Houston County
• 
  Sarracenia spiketail (Cordulegaster sarracenia) Rapides Parish, Louisiana