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When European explorers first came to Arkansas, they found the vast majority of the state covered by some type of forest or woodland. In general, the upland areas of the state were covered by shortleaf pine-oak-hickory forests in areas underlain by acidic rocks (primarily sandstone and chert) and by oak-hickory forests in areas underlain by neutral to calcareous rocks (primarily limestone and dolomite). Lowland areas of eastern and southern Arkansas were covered primarily by bottomland hardwood forests, with baldcypress-tupelo swamps in the wettest areas. The Gulf Coastal Plain of southern Arkansas was covered by a mix of forest types, but with loblolly and/or shortleaf pine dominant in many areas. Within these general forest types were hundreds of species of woody plants and at least 160 species of trees.
As of 2010, 360 species of woody plants are known to occur in the wild in Arkansas. About 190 can be considered trees, with the balance more appropriately classified as shrubs or woody vines. It is difficult to draw a hard line between small trees and large shrubs, though shrubs can be defined as short (eight feet and shorter) woody plants, usually with multiple trunks, while trees can be defined as tall (eight feet and taller), usually with single trunks. Still, there are some gray areas. Thirty of the trees found in Arkansas today are not native to the state and were introduced either accidentally or on purpose from elsewhere in the world since the time of European settlement.
The largest genera of trees in Arkansas are the oaks (Quercus, twenty-nine tree species), the hawthorns (Crataegus, eighteen species of mostly small trees), the hickories (Carya, ten species), the plums and cherries (Prunus, eight tree species), the maples (Acer, seven species), the elms (Ulmus, seven species), the willows (Salix, six tree species), the pines (Pinus, six species), the magnolias (Magnolia, five species), and the ashes (Fraxinus, five species). Two species of native pine trees are widely distributed in Arkansas and are of great economic importance. Shortleaf pine (Pinus echinata) is a dominant species in large areas of the Interior Highlands (Ozark and Ouachita mountains) but is also widespread in the Gulf Coastal Plain. Loblolly pine (Pinus taeda) has been planted throughout the state but is considered native to the Gulf Coastal Plain, with a few rare pockets of natural occurrence in the Mississippi Alluvial Plain and Ouachita Mountains. Several other species of pine have been occasionally planted in Arkansas but are not naturalized to any great extent.
Oaks are also of great importance, both ecologically and economically, in the forests of Arkansas. Thirty species of oaks are known to grow in the state, twenty-nine of which are trees, and twenty-seven of which are considered native. The most common and widespread upland oak species in the state are white oak (Quercus alba), post oak (Q. stellata), blackjack oak (Q. marilandica), southern red oak (Q. falcata), northern red oak (Q. rubra), chinquapin oak (Q. muhlenbergii), and black oak (Q. velutina). Common lowland oaks include willow oak (Q. phellos), water oak (Q. nigra), swamp chestnut oak or cow oak (Q. michauxii), Nuttall oak (Q. texana), cherrybark oak (Q. pagoda), and overcup oak (Q. lyrata). Hickories are also common in most of Arkansas’s natural forests, with mockernut hickory (Carya tomentosa), black hickory (Carya texana), and pignut hickory (Carya glabra) common on drier sites, while bitternut hickory (Carya cordiformis), shagbark hickory (Carya ovata), and kingnut or shellbark hickory (Carya laciniosa) are more common in moist sites. Water hickory or bitter pecan (Carya aquatica) occurs in the wettest bottomland hardwood forests.
Some native tree species are colonizers of disturbed sites such as abandoned pastures and crop fields, cutover forests, and roadsides. Common examples of these pioneer species in Arkansas include eastern redcedar (Juniperus virginiana), sweetgum (Liquidambar styraciflua), sassafras (Sassifras albidum), honeylocust (Gleditisa triacanthos), black locust (Robinia pseudoacacia), smooth sumac (Rhus glabra), winged sumac (Rhus copallinum), and persimmon (Diospyros virginiana). Other species are typically found along major streams and rivers where natural disturbance from flooding favors species that reproduce abundantly and grow quickly. Examples of such riverine species include black willow (Salix nigra), eastern cottonwood (Populus deltoides), river birch (Betula nigra), sycamore (Platanus occidentalis), boxelder (Acer negundo), silver maple (Acer saccharinum), and green ash (Fraxinus pennsylvanica). Swamps that are flooded for long durations are often dominated by swamp tupelo or tupelo gum (Nyssa aquatica) and/or baldcypress (Taxodium distichum), both of which can withstand nearly permanent water once they are established.
Upland forests, while often dominated by pine, oak, and hickory are also occupied by many other tree species. Common species include black gum (Nyssa sylvatica), hop hornbeam or ironwood (Ostrya virginiana), serviceberry (Amelanchier arborea), flowering dogwood (Cornus florida), Mexican plum (Prunus mexicana), black cherry (Prunus serotina), redbud (Cercis canadensis), red maple (Acer rubrum), red buckeye (Aesculus pavia), Devil’s walking stick (Aralia spinosa), rusty blackhaw (Viburnum rufidulum), and white ash (Fraxinus americana). In more moist or nutrient-rich sites, other species may be found, including black walnut (Juglans nigra), American beech (Fagus grandifolia), pawpaw (Asimina triloba), American holly (Ilex opaca), deciduous holly (Ilex decidua), sugar maple (Acer saccharum), Ohio buckeye (Aesculus glabra), and basswood (Tilia americana).
Arkansas is home to two trees that are thought to be unique to Arkansas. Maple leaf oak (Quercus acerifolia) is a small tree known from just four mountaintops in the Ouachita Mountains and Arkansas Valley, where it is confined to high-elevation dry woodlands. Stern’s medlar (Crataegus × canescens, formerly Mespilus canescens) is known from a single site in the Grand Prairie region of eastern Arkansas, where just twenty-six individual trees of the species are known to exist. Recent genetic research into this population suggests that the species may be of hybrid origin—the result of past hybridization between the native blueberry hawthorn (Crataegus brachyacantha) and the European medlar (Mespilus germanica), which was presumably brought to the area by immigrants from eastern Europe.
Not all of the tree species found in Arkansas are native to the state. Several of these non-native trees are considered by botanists and ecologists to be invasive in Arkansas’s natural communities, capable of displacing native vegetation and altering habitat for native wildlife. Examples of non-native invasive trees in Arkansas include Chinese tallow tree (Triadica sebiferum), silktree (Albizia julibrissin), Chinaberry (Melia azedarach), Chinese privet (Ligustrum sinense), empress tree or princess tree (Paulownia tomentosa), callery pear (Pyrus calleryana), and tree-of-heaven (Ailanthus altissima).
Diverse forests with the full range of tree species typical of pre-settlement Arkansas have declined in the last century as parts of the state were largely cleared for agriculture, converted to single-species (primarily loblolly pine) plantation forestry, or developed. Some forest and woodland types are still widespread and abundant, but others have declined enough to be of conservation concern. Forest types that have experienced the greatest decline are those that are restricted to geographic regions where their geology, soils, climate, topography, and location have made them highly profitable for conversion to other uses. Examples of these forest types include the bottomland forests of eastern Arkansas, the oak barrens and glades of the igneous rock areas of Saline and Pulaski counties, the oak savannas of northwestern Arkansas and the Grand Prairie region, and, more recently, the pine flatwoods of the Gulf Coastal Plain.
Several Arkansas tree species have been dramatically reduced from their historical levels due to the introduction of diseases or pests from other regions of the world. The most well-known example is the decline of Arkansas’s two native chinquapins (Castanea pumila var. pumila and C. pumila var. ozarkensis) as a result of the chestnut blight, a fungal pathogen accidentally introduced from Asia in the early twentieth century. Other examples include the dramatic decline of butternut, or white walnut (Juglans cinerea), in recent decades from butternut canker disease, as well as the more modest decline of American elm (Ulmus americana) due to Dutch elm disease. Many ecologists and foresters are currently concerned about the recent detection in Arkansas of dogwood anthracnose (a fungal disease presently causing a decline in flowering dogwoods in the eastern United States) and the detection in southern Missouri of the emerald ash borer (an introduced insect that is killing all species of ash trees in the upper Midwest).
Twenty-two tree species in Arkansas have been identified as species of conservation concern by the Arkansas Natural Heritage Commission. These species are rare in the state and may be at risk from loss of habitat, disease, or other factors. The following table lists the trees of conservation concern in the state. (Note that shrubs of conservation concern are not listed.)
Acer saccharum var. leucoderme
Acer saccharum var. nigrum
Castanea pumila var. ozarkensis
Capul Negro, Brasil
Crataegus × canescens
butternut, white walnut
maple leaf oak
For additional information:Arkansas Vascular Flora Committee. Checklist of the Vascular Plants of Arkansas. Fayetteville: University of Arkansas Herbarium, 2006.
Hunter, Carl G. Trees, Shrubs, and Vines of Arkansas. Little Rock: Ozark Society Foundation, 2004.
Smith, Edwin B. Keys to the Flora of Arkansas. Fayetteville: University of Arkansas Press, 1994.
Smith, Kenneth L. Sawmill: The Story of the Cutting of the Last Great Virgin Forest East of the Rockies. Fayetteville: University of Arkansas Press, 1986.
Tucker, Gary Edward. “A Guide to the Woody Flora of Arkansas.” PhD diss., University of Arkansas, 1976.
Theo WitsellArkansas Natural Heritage Commission
Last Updated 5/13/2011
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