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202 BOTANICAL GAZETTE [SEPTEMBER 
The plains prairies —To the northwest there is an area of the 
Edwards plateau which has not yet come to the stage of active 
and deep erosion, but is a typical open level plains country, with 
low relief lines of erosion remnants, and draws which lead into 
the cafions of the southern erosion area. This plains prairie is 
embraced approximately in the counties of Upton, Glasscock, 
Stirling, Concho, Crockett, Sutton, Schleicher, Tom Green, and 
Irion. 
This Cretaceous area, both by its altitude and its westerly 
position, shares climatic conditions to a marked degree with the 
Stockton plateau and the Staked plains. Asa result, the grass 
vegetation is of a more xerophytic character than in any of the 
provinces previously discussed. It is, in fact, almost fairly 
within the ‘short grass” country. Like the Grand prairie, this 
Cretaceous formation increases the xerophytic tendencies, so 
that here we find again a strong element in the perennial vege- 
tation, which is more suffruticose than herbaceous, and made up 
of species with more xerophytic aspect and with affinities to the 
flora of the trans-Pecos provinces, But this element is in every 
way the counterpart of the chalk soil lignescent vegetation of 
the Grand prairie. In addition, the chaparral formations of the 
Stockton plateau and southwestward are encroaching upon this 
area. 
Tue STakeED pLains.—The Staked plains of the Texas region 
are simply a continuation southward of the Great plains area of 
western Nebraska, Kansas, and eastern Colorado, but cut off 
from the main area by the deeply eroded channels of the Cana- 
dian river on the north, and the Pecos on the west. To the 
north of the cafion of the Canadian river, Texas contains also 4 
portion (the Pan Handle) of the main body of the plains. 
“This province is a vast constructional plain made up of flood 
débris from the mountains at whose base it lies. This mass of 
loose unconformable stuff is a monotonously flat plateau plain, 
whose only surface relief is the billowy swells and’ the shallow 
saucer-like depressions” (Hill). The open, porous, often sandy 
texture of the soil furnishes a favorable receiving area for 
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