16; 



TABLE V. BLOW-SAND. 



Oycloloma atriplicifolium 

 (Cassia chamaecrista 

 Euphorbia Geyeri 

 Oenchrus tribuloides 

 Oommelina virginica 



TABLE VI. BLOW-SAND. 



Cassia chamaecrista 

 Ambrosia psilostachya 

 Euphorbia Geyeri 

 Oommelina virginica 

 Oenchrus tribuloides 

 Oroton glandulosus 

 Cristatella Jamesii 



g*f b o o 



e e d o o 



c d b o o 



a a o a o 



e a o o o 



a o o o o 



a o o o o 



TABLE VII. BLOW-SAND. 



Oycloloma atriplicifolium 

 Cassia chamaecrista 

 Ambrosia psilostachya 

 Oenchrus tribuloides 



f*f g a f 



c e g g f 



f e e e c 



o o o o a 



THE BLOWOUT ASSOCIATION. 



When the excavation of the blowout has proceeded so far 

 that the maximum depth is reached, the blowout association 

 is developed at the bottom, in response to the changed ecolog- 

 ical conditions. These are (1) a slight protection from the 

 wind, (2) a more stable substratum, and (3) a larger supply 

 of soil moisture. The result is an association essentially meso- 

 phytic in nature. Most of the members of the blow-sand asso- 

 ciation, excepting Cycloloma and Cristatella, persist for a time, 



* See p. 159. 



