Texas-Louisiana Coastal Prairie

Geology

This system is generally coincident with the distribution of the Pleistocene Beaumont and Lissie Formations.

Landform

Usually on level to gently rolling landscapes, with slopes generally less than 5%. Microtopography plays an important role in local variation in the system, with ridges, swales, mounds, depressions, mima (or pimple) mounds, and gilgai leading to a mosaic of drier and wetter plant communities.

Soils

Non-saline Vertisols, Alfisols, and (less extensively) Mollisols. Vertisols are often characterized by gilgai, resulting from shrink-swell attributes of the montmorillonitic clays of which they are composed. The Alfisols have a loamy surface with clayey subsoils.

Parent Description

This mid- to tallgrass prairie occupies Pleistocene surfaces of the Texas and Louisiana coast, on non-saline soils of level to gently rolling topography. It is dominated by graminoid species, such as Schizachyrium scoparium (little bluestem), Sorghastrum nutans (Indiangrass), Paspalum plicatulum (brownseed paspalum), Panicum virgatum (switchgrass), Andropogon gerardii (big bluestem), Sporobolus compositus (tall dropseed), Paspalum setaceum (thin paspalum), Fimbristylis puberula (hairy fimbry), Dichanthelium oligosanthes (fewflower panicgrass), Rhynchospora spp. (beaksedges), Paspalum floridanum (Florida paspalum), Muhlenbergia capillaris (Gulf muhly), Tridens strictus (longspike tridens), Bouteloua curtipendula (sideoats grama), Andropogon glomeratus (bushy bluestem), and Tripsacum dactyloides (eastern gamagrass). Axonopus spp. (Carpetgrasses), Sporobolus indicus (rat-tail smutgrass), Andropogon virginicus (broomsedge bluestem), Bothriochloa laguroides ssp. torreyana (silver bluestem), and Nassella leucotricha (Texas wintergrass) may be particularly noticeable on over-grazed sites. Non-native graminoids that may be conspicuous to dominant components include Cynodon dactylon (bermudagrass), Cyperus entrerianus (deep-rooted sedge), Bothriochloa ischaemum var. songarica (King Ranch bluestem), Dichanthium spp. (old world bluestems), Lolium perenne (Italian ryegrass), Schedonorus phoenix (tall fescue), Paspalum notatum (bahiagrass), and Paspalum dilatatum (dallisgrass). Forbs that may often be encountered include Liatris spp. (gayfeathers), Sabatia campestris (meadow pink), Ambrosia psilostachya (western ragweed), Euphorbia bicolor (snow-on-the-prairie), Solidago spp. (goldenrods), Rudbeckia hirta (Blackeyed Susan), Ruellia humilis (low wild petunia), Asclepias viridis (green milkweed), Chamaecrista fasciculata (partridge pea), Helianthus angustifolius (narrowleaf sunflower), Euthamia spp. (goldentops), Ratibida columnifera (Mexican hat), Symphyotrichum ericoides (heath aster), Silphium laciniatum (compass plant), Baptisia spp. (wild indigos), Iva angustifolia (narrowleaf sumpweed), Eryngium yuccifolium (button snakeroot), Boltonia diffusa (smallhead doll's daisy), and Neptunia lutea (yellow neptunia). Woody species may invade this typically herbaceous vegetation, including Rosa bracteata (Macartney rose), Acacia farnesiana (huisache), Triadica sebifera (Chinese tallow), Baccharis halimifolia (baccharis), Celtis laevigata (sugar hackberry), and Prosopis glandulosa (honey mesquite).