winter temperatures in west Texas from those of southern Texas 

 may account for the plant's rarity. 



The cHmate of southern Texas is semiarid to subhumid sub- 

 tropical, the northern optimum climate for Peyote abundance in 

 North America. Climatic variables in south Texas which limit the 

 abundance of the plant are drought and perhaps excess rainfall. 

 Cyclical midsummer droughts combined with heat waves and 

 high insolation rates scorch the vegetation; under such climatic 

 stresses Peyote is one of the last plants to lose its chlorophyll 

 pigmentation. 



During dry periods many Peyote plant-crowns descend below 

 the ground surface, thus reducing exposure to transpiration 

 losses. The greater surface area of large, older plant-crowns, 

 especially those that do not retreat below the surface, are more 

 vulnerable to blistering, parching, and bleaching during a pro- 

 longed heat wave. The rainfall regime of south Texas is character- 

 ized by a double maximum; June rains followed by higher rainfall 

 totals in September. Flooding sometimes accompanies the Sep- 

 tember rains which are associated with hurricanes. A Peyotero 

 claimed that the root system of many Peyote rotted in the ground 

 because of excessive rains and flooding during hurricane "Beu- 

 lah^in 1967(Davila, 1974). Canadian "northers" frequent south 

 Texas in the winter months, but the majority of these cold waves 

 are considerably warmed when they reach the south Texas plains; 

 their duration is brief. Occasionally, a "norther"does damage to 

 the large subtropical plants but losses to plants of smaller stature, 



such as Peyote, are reportedly less. 



Field investigation indicates that Peyote is more abundant on 

 east and south-facing slopes. East-facing slopes receive more 

 moisture from prevailing southeast Gulf winds. During early 

 morning hours, low stratus clouds moisten the vegetation (fig. 2). 

 South-facing slopes are more protected from cold waves in winter 

 and warm up earlier in spring. 



Peyote harvested by Peyoteros and Indians, today and in the 

 historic past, occurs in four counties of south Texas: Starr, Jim 

 Hogg, Webb, and Zapata. Within these four counties, the range 

 of the plant with densities large enough to be commercially signif- 

 icant occurs along the western margins of the Bordas Escarp- 



75 



