Vegetation oe the Sotol Country. 
115 
Boerhaavia decumbens and Wrightii; Lesquerella species; 
Cevallia sinuata; Gilia species, Krynitzkia species, Nama 
hispidnm ; Baileya mnltiradiata, Sartwellia flaveriae, 
Perezia nana. 
D. Ecological forms which have the capacity of becoming dor- 
mant by virtual encystment of their living substance, accom- 
panied by the rolling together of the leaves of the entire plant. 
Typical and most common is Selaginalla lepidophylla. S. 
rupestris also, and several Cyanophyceae, lichens belong 
here. One or more thallose liverworts and perhaps a 
dozen species of ferns found on rock ledges in the canyons 
possess the capacity to dry out and roll up most com- 
pletely — e. g., Cheilanthes and Notholaena. 
E. The Grass Type: Annuals or perennials, the latter probably 
predominating but with no special food storage. During rain- 
less periods the stems and leaves die and become thoroughly 
cured standing. After rainfall, new shoots quickly appear 
from dormant buds of perennials and from seed of annuals. 
See list of grasses, pp. 9, 10. 
The sotol formation of the West Texas region is thus found to be 
composed of a flora varying with the locality from one hundred to 
a few hundred species falling into a small number of adaptation 
forms. These several forms do not all play an equal part in the 
vegetation in the sense of being equally numerous or equally con- 
spicuous. Thus the cactus type which is popularly supposed to 
represent the ideal desert plant, is by no means so abundant or so 
conspicuous as it is in the vegetation of many parts of the Rio 
Grande Plain although there are many more species of cacti in the 
sotol formation. It must be said, however, that the species of cacti 
represented in the sotol formation are not conspicuous plants and 
that their numerical representation in the flora, is really much 
greater than seems apparent. In general, the very types that 
would be selected as the fittest adaptations to arid habitats — with 
the exception of lechuguilla — are those of relatively infrequent oc- 
currence — e. g., Fouquiera, Koeberlinia, Arioearpus, Ephedra. 
Preference is also shown by different types for different conditions 
of soil and topography, and consequently their part in the whole 
vegetation would vary with the extent of the particular feature 
with which they are identified. Thus the broad divides or long 
slopes are the most extensive physiographic feature and sotol which 
selects such areas is also the most abundant single type. The round 
topped points or sharply sloping rock-strewn hillsides afford abun- 
./ 
