30 AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS. 



The Edwards Plateau is a common meeting ground for species from 

 the Atlantic forest belt, the southern Eocky Mountains, and the north 

 Mexican highlands. Ninety species of trees and shrubs have been 

 recognized in this region. Many Atlantic species, surviving conditions 

 found here, have become permanently changed into new species, though 

 showing close kinship. A discussion of the commercial species is best 

 given under the three prevailing conditions of forest found, namely: 

 the timber of the streams and canyons, the hill and bluff timber, and 

 the prairie timber. 



Timber of the Streams and Canyons. 



Many of the species found along the streams which flow through the 

 Edwards Plateau or which flow from springs along the eastern escarp- 

 ment are those of the Atlantic flora, extensions of the eastern bottom- 

 land type. One is amazed to find within these canyon bottoms cypress 

 of the East Texas swamps and bayous growing to several feet in diam- 

 eter. Cypress at one time was -abundant and much of the early con- 

 struction in San Antonio and other sections near the canyon bottoms 

 was of this species. American elm, sycamore, live oak, pecan, overcup, 

 red, burr, and other oaks, cottonwood, hackberry, and walnut are among 

 the most valuable species found in this type. Other species of interest 

 are black cherry, dogwood, and box elder. Many of tfie narrow alluvial 

 bottoms which formerly supported these species are now cleared along 

 the principal streams flowing out of the Edwards Plateau. The culti- 

 vation of native pecan is a recognized industry and along the stream- 

 ways of most of this region, particularly in the San Saba country, excel- 

 lent groves of native trees are found which bring large returns to their 

 owners. Live and burr oaks, four to five feet in diameter, are not 

 uncommon. 



Hill and Bluff Timber. 



This represents by far the greater part of the timberland of the 

 region. On the limestone hills it occurs in varied forms wherever 

 erosion or dissection has^taken place. Along the breaks of the streams, 

 on steep slopes and rough hills, and on isolated limestone remnants of. 

 the Edwards Plateau far to the north and northwest of the main body, 

 a mixed forest of mountain cedar, live oak, mesquite, cedar elm, hack- 

 berry, mountain oak, shin oak, sumac, and other species prevails. On 

 the more level uplands mixed forests of the same general character are 

 found, but they are interspersed with grassy areas and are more scrubby. 

 Timbercapped buttes are a feature of the Burnet and Lampasas sec- 

 tions. In such places the debris covered, lower slopes are too unstable 

 to permit the capture of the soils by timber growth. 



Several of the species composing these mixed forests are commonly 

 found growing in nearly pure stands or else under different conditions 

 of growth and density. They thus form well recognized types, such as 

 the shinneries, mountain oak thickets, post oak areas, and the cedar 

 brakes. The shinneries are dense, dwarf thickets of shin oak, with 



