REGION BY REGION MAP
From the Pineywoods of East Texas with 60 inches of rain annually to the West Texas Chihuahua Desert with 8 inches/year, Texas has 10 ecological zones, each with its own distinctive vegetative association. The range of many wildflower species roughly follows the 5 geographical regions chosen here, but plants don’t always respect arbitrary boundaries. Many grow in more than one region and some occur statewide, while others are limited on the planet to only a few Texas counties. These statewide guidebook highlights more than 700 of the most common wildflowers seen, as well as significant rare and endangered species.
East Texas
The wettest region of Texas receives 60 inches of rain annually with a summer climate that exceeds 90 degree F. and 90 percent humidity, and winters with seldom hard freezes. The dense pine-hardwood woodlands of the Pineywoods covers the east, including Big Thicket, one of the most biodiverse regions in North America. The Post Oak Savannah separates the Pineywoods and the Blackland Prairie of north-central Texas (DFW). Coastal Prairies and Marshes border Gulf coast.
Texas Hill Country
This section of Texas includes the counties of the Edwards Plateau, a limestone uplift dissected by eroded canyons bounded by the Balcones Escarpment (IH-35) to the east and the Pecos River to the west, and the Llano Uplift, an area of granite soils with a distinctive vegetative community. Waco and Abilene form the northern border and San Antonio and the South Texas Plains the southern border.
North Texas–Panhandle, Prairies, and Plains
This region covers the botanically diverse Panhandle, composed of the High Plains (Llano Estacado) and Rolling Plains, and the north Texas Blackland Prairies (DFW area) interspersed with the oak woodlands. Many of the Shortgrass and Tallgrass Prairie species of the Great Plains reach their southern limits here.
South Texas
Extending south from a line connecting Del Rio, San Antonio, and Victoria, the sub-tropical South Texas Region rarely experiences extended freezes. It includes three major vegetation communities with 1,200 species of plants documented. The Coastal Prairies and Marshes extend inland along the Gulf coast from Louisiana to Brownsville and encompass Victoria, Calhoun, Refugio, San Patricio, Neuces, and most of Kleberg counties. Sand washed down the Rio Grande forms the barrier islands and lagoons along the coast. Prevailing winds blow the sand inland to create the South Texas Sand Sheet. Deep deposits cover Kennedy, Brooks, and parts of Klebreg, Jim Wells, Jim Hogg, Starr, Hidalgo, and Willacy counties. The South Texas Brush Country, a sub-tropical thorn forest community, covers the Rio Grande Valley and central portion of the region. Ninety-five percent of the Rio Grande Valley has been cleared for farmland.
Trans-Pecos
The area west of the Pecos River in west Texas falls completely within the Chihuahua Desert, which extends deep into Mexico. Though averaging less than 8 inches of rain annually, it is one of the richest deserts in the world. More than 1,500 plant species occur in the U. S. With desert basins and entire mountain ranges, the Trans-Pecos varies from 820 feet at the Rio Grande to 6,562 feet in Big Bend National Park and 8,751 in Guadalupe Mountains National Park. Besides two of the most biodiverse national parks in the nation, it includes Big Bend Ranch and Davis Mountains state parks. From arid low desert to moist mountain tops, plants have specialized in the many micro-habitats and often have very limited distribution.
