VEGETATIONAL AREAS OF TEXAS

FRANK W. GOULD, TEXAS AGRICULTURAL EXPERIMENT STATION GARLYN O. HOFFMAN, TEXAS AGRICULTURAL EXTENSION SERVICE TEXAS A&M UNIVERSITY CLARENCE A. RECHENTHIN, SOIL CONSERVATION SERVICE, USDA

~he map showing vegetational areas was rye, Elymus virgtntcus, Canada wildrye, E. developed primarily as a basis for recording canadens is, purpletop, Tr idens f lavus, broad­ the general distribution of plants and dis­ leaf uniola, Uniola latifolia, spike uniola, tingui shing maj or vegetation types on the U. laxa, pineland bluestem, Andropogon sco­ 169,000,000 acres of Texas. These areas are parius var. divergens (A. divergens of Hitch­ based on topographic, climatic and soil fac­ cock's Manual), switchcane, Arundinar ia gigan­ tors and generally correspond with the areas tea, brownseedpaspalum, Paspalum plicatulum, shown in L-400, Land Resource Areas of Texas. and many species of Panicum. Typical prairie Ten areas are presented as the divisions of vegetation is present on restricted clay vegeta~ional types based on the present work­ prairie sites. ing knowledge of native flora. The most complex pattern of plant association occurs 2. Gulf Prairies and Marshes in the north-central portion of the State where the vegetation of land resource areas This area comprises approximately 9,­ of the Grand Prairie, the East and West Cross 500,000 acres of Gulf Prairies and 500, 000 Timbers and the North Central Prairies inter­ acres of Gulf Marshes. The principal climax mingle. It is recognized that continued stud­ plants of the prairie sites are tall bunch­ ies of vegetational structure in the diversi­ grass, including big bluestem, Andropogon ty of habitats in Texas may provide basi s for gerardi, seacoastbluestem, A. scoparius var. future modification of these areas. littoralis (A. littoralis of Hitchcock's Manual), Indiangrass, Sorghastrum nutans, A brief summary of characteristics of eastern gamagrass, Tripsacum dactyloides, the 10 vegetational areas follows. The pre­ switchgrass, Panicum virgatum, and gulf cord~ dominant plants for each vegetational area grass, Spart ina spart inae. Seashore saltgrass._ in general are the ones growing on good and Distichlis spicata, is frequent on moist sa­ poor condition rangeland. Plants are refer­ line sites. red to by their common names, with scienti­ fic names listed in i tali cs at first refer­ ence. TAES MP-585, Texas Plants--A Checklist 'The vegetation of the Gulf Marshes con­ and Ecological Summary, was used as a guide sists primarily of species of Carex, Cyperus, in the selection of plant names. Rhynchospora, Scirpus, Juncus and marshhay cordgrass, Spart ina patens. Marsh mi llet, 1. Pineywoods Zizaniopsis miliacea, is frequent in dense stands. This area contains approximately 16,­ 000,000 acres of mixed pine-hardwood forest, wi th pine being the fire subclimax. The maj or 3. Post M Savannah commercial timber species are loblolly pine, Pinus taeda, shortleafpine, P. echinata, This area contains approximately 9, 000, ­ longleaf pine, P. palustris, and slash pine, 000 acres. The climax vegetation was basically P. elliot t i i. The principal grasses are mainly a savannah type. Due to intensive grazing species of Panicum, Paspalum and Andropogon. practices, much of this area has degenerated Frequent in forest association are blackseed to dense stands of oak brush with an under­ needlegrass, Stipa avenacea, Virginia wild- story of yaupon, Ilex vomitoria. The climax grass vegetation consists chodes, Indiangrass, switchgrass and many mainly of little bluestem~ Andropogon scopa­ species of legumes and palatable forbs. rius, Indiangrass. switchgrass, purpletop, a variety of silver bluestem, Andropogon saccharoides, Texas wintergrass, St ipa leuco­ 6. South Texas Plains tricha, spike uniola, longleaf uniolaf Unio la sessiliflora, post oak, Quercus stellata~ and This region comprises approximately blackjack oak, Q. marilaruiica. 20,000,000 acres of mostly level terrain but with diverse soil types and sites. The origi­ nal vegetation was comprised mainly of peren­ 4. Blackland Prairies nial warm-season bunchgrasses in post oak and Iive oak, Quercus v irginiana, frequently with Area 4 contains approximately 11,500,­ mesquite Prosopis spp., and other brush 000 acres, with black clay-loam soil developed species forming dense thickets on the ridges. under prairie grass-forb vegetation. For the Long-continued grazing has altered the vege­ most part, this fertile area has been brought tation to such a degree that now the region under cultivation and only small acreages of is known as the "brush country." Most of the meadowland remain in climax tall grass vege­ desirable grasses have persisted under the tation. In heavily grazed pastures, the tall protection of brush and cacti. bunchgrasses have been replaced by buffalo­ O1aracteristic grasses of the sandy loam grass, Buchloe dactyloides, Texas grama, soils are seacoast bluestem, species of Boute loua rigidise t a, and other grasses of Setaria, Paspalum, Chloris and Trichloris# lower productivity. silver bluestem, big sandbur, Cenchrus myo­ The climax grass vegetation includes suroides, and tanglehead, Heteropogon contor.. little and big bluestem, Indiangrass, switch­ tus. The dominant grasses on the clay and clay grass, sideoats grama, Boute loua curt ipendu la, loams are silver bluestem.Arizonacottontop, hairy grama" B. hirsuta, tall dropseed, Trichachne californica, buffalograss, curly­ Sporobolus asper, Texas wintergrass and buf­ mesquite, Hilaria belangeri, and species of falograss. The prairie forb vegetation is Setaria, Pappophorum and Boute loua. Low saline comprised largely of legumes and composites. areas are characterized by gulf cordgrass, seashore saltgrass, alkali sacaton, Sporobo lus airoides, and switchgrass. In the post oak 5. Cross Timbers and Prairies and live oak savannahs, the grasses are mainl'y seacoast bluestem, Indiangrass, switchgrass, Region 5 comprises approximately 16,· crinkleawn, Trachypogon securuius, and species 500,000 acres of closely associated prairie of Paspalum. and woodland sites. Sharp changes in the vegetational cover are associated with dif­ 7. Edwards Plateau ferences in soils and topography. In many areas, however, there is an intermingling of This area is the West Central Texas vegetational types. "Hill Country" of some 24,000,000 acres. The Edwards Plateau is a region of limestone out­ The climax prairie vegetation is com­ crops and rocky but fertile soil. In the east­ prised primarily of big and little bluestem, central portion is the well marked "Central Indiangrass, sideoats grama, blue grama, Basin" {centering in Mason, Llano and Burnet Bouteioua gracilis, and buffalograss. counties}, with a mixture of granitic and sandy soils. The western portion of the area On the predominantly sandy soils of the is comprised of the semi-arid Stockton Plateau Cross Timbers, the woodland vegetation is which has an annual rainfall of 18-20 inches dominated by shinneryoak, QJ.ercus spp., post or less. oak and blackj ack oak. The climax herbaceous vegetation is composed of big and Iittle The principal climax grasses of this bluestem, sand lovegrass, Eragrostis triM are'a are cane bluestem, Andropogon barb inodis, sideoats grams silver bluestem, Iittle bluestem, sideoat.s bluestem,/western wheatgrass, Agropyron and hairy grama, Indiangrass, curlymesquite, smithii, Indiangrass and switchgrass on the buffalograss, fall wi tchgrass, Lepto loma sandy loam soi Is. Shinnery oak and sand sage­ cognatum, and species of Tridens and Elymus. brush are conspicuous on sandy sites. Several Tobosa, Hi laria nautica, forms dense stands on species of dropseeds , Sporobo l·us spp., are the Stockton Plateau. abundant on coarse sands in the southern portion. Throughout the Edwards Plateau, live oak, shinnery oak, mesquite and species of 10. Trans-Pecos, Mountains and Basins Juniperus dominate the woody vegetation. This area of approximately 18,000,000 acres includes most of the region west of the 8. Rolling Plains Pecos Ri ver. It is made up mai~l y o( arid This area has approximately 24,000,000 valleys~plateausand mountains. The mountains acres of rolling-to-rough top:>graphy and mixed are 3,000 to 8,000 feet in elevation and grassland vegetation. Soils range from coarse support ponderosa pine, Pinus ponderosa, for­ sands along outwash terraces adj acent to est vegetation on a few of the higher slopes.. streams to tight or compact clays on red bed The principal vegetation types are the creo­ clays and shales. Rough, broken lands on steep sote bush, Larrea divaricata, and tarbush, slopes are found in the western portion. Flourens ia cernua, desert shrUb, grama grass­ land, Yucca and Juniperus savannahs, and pinon The principal climax grasses are mix~ pine, Pinus edulis and P. cembroides, and oak tures of big and little bluestem, sand blue­ forest. Alkali sacaton and species of salt­ stem, Andropogon hallii, sideoats grama, bush, Atrip lex, are present on the saline Indiangrass and switchgrass in the more sandy soils. soils. Sideoats and blue grama, tobosa and buffalograss are dominant on the tighter The grass vegetation, especially on the soils. Mesquite is a common invader on all higher mountain slopes, includes many south­ soils. Shinnery oak a nd sand sagebrush, western and Rpcky Mountain species not present Artemisia filifolia, are common on the deep elsewhere in Texas. On the desert flats, sands. black grama, Bouteloua eriopoda, burrograss, Scleropogon brevifolius, and fluffgrass, 9. High Plains Tridens pi losus, are frequent. More productive sites have numerous species of grama, muhly, Area 9 contains approximately 20,000,000 Muhlenbergia, dropseed and perennial threeawn, acres of level-to-slightly rolling plains with Aristida, grasses. At the higher elevations, highly fertile clay and sandy soils. little bluestem and Texas bluestem, Andropogon cirratus, sideoats and blue grama, pinon rice­ Blue grama and buffalograss comprise grass, Piptochaetium fimbriatum, wolftail, the principal vegetation on the clay and clay Lycurus phleoides, and several species of loam sites. Other important grasses are little Stipa ~re frequent.

Cooperative Extension Work in Agriculture and Home Economics, The Texas A. & M. College System and United States Department of Agriculture cooperating. Distributed in furtherance of the Acts of Congress of May 8, 1914, as amended, and June 30, 1914. June 1960