VEGETATIONAL REGIONS OF TEXAS
Vegetational Regions of Texas
2. Gulf Prairies and Marshes
3. Post Oak Savannah
4. Blackland Prairies
5. Cross Timbers and Prairies
6. South Texas Plains
7. Edwards Plateau
8. Rolling Plains
9. High Plains
10. Trans-Pecos, Mountains and Basins
The makeup of a particular flora (flora = sum of plant species in a
particular region or zone) is affected by many factors:
A. Rainfall - total amount & pattern
B. Temperature - Av. temp.'s & rate of change.
C. Latitude and elevation.
2. SOIL TYPES
3. DISTURBANCES, ESPECIALLY HUMAN
4. PLANTS THEMSELVES CAN AFFECT OTHER PLANTS
A. Allelopathy - production of substances toxic to plants
B. New invaders (weeds)
5. FAUNA INTERACTS WITH FLORA
FLORA(S) OF TEXAS
A great variety of rainfalls (8' to 56"), elevations, (sea level to
8751') and soil types have resulted in a very diverse flora (for
temperate areas) of about 5500 species.
I. TIMBER BELT - PINEYWOODS AND EAST TEXAS FOREST REGION
A. 200' to 500', rolling hills, large rivers, 35 to 50" rain, acid
B. Composition is pine and pine-hardwood forest with intermittent
C. Southwestern terminus of forest that extends east to Florida and
northeast to Virginia.
D. Flora is very similar to southeastern states.
II. GULF PRAIRIES AND MARSHES
A. Level plain <150', with sluggish rivers, creeks, bayous and
sloughs, 30 to 50" rain.
B. Climax vegetation is grassland or post oak savannah but many other
plants have invaded.
III. POST OAK SAVANNAH
A. Gently rolling to hilly, 300 to 800', 35 to 45" rain, highly
B. May have had more of a prairie composition before settlement, now
has a large tree and shrub component.
IV BLACKLAND PRAIRIES
A. Level to gently rolling, 300 to 800', 30 to 40" rain.
B. Dominant plant species are grasses but also much timber
V. CROSS TIMERS AND PRAIRIES
A. North central prairies, 25 to 40" rain, diverse soil types.
B. Dominant vegetation type is grassland but dense brush covers some
areas and mesquite is well-established.
VI. RIO GRANDE PLAINS
A. Level to rolling, sea level to 1000', 16 to 30" rain with
B. Open prairies with many small trees and shrubs.
VII. EDWARDS PLATEAU - HILL COUNTRY
A. Hilly, 1000 to 3000', 15 to 33" rain, frequent drouths, soils are
shallow and underlain by limestone, caliche, granite, or gneiss.
B. Climax vegetation is grassland or open savannah but many brushy
species have invaded.
VIII. ROLLING PLAINS
A. Elevation is 800 to 3000', 22 to 30" rain with summer dry period,
many soil types.
B. Prairies with many invaders due to overgrazing.
IX HIGH PLAINS (VIII + IX= PANHANDLE)
A. Level high plateau, 3000 to 4500', 15 to 21" rain with extended
B. Vegetation is mixed prairies to short-grass prairie.
X TRANS-PECOS, MOUNTAINS, & BASINS
A. Diverse habitats and regions, 2500 to 8500', <12 to 20" rain,
B. Many vegetation types from desert to conifer forests.
More information on Texas Vegetational Regions is
available from the