40 



THREE 



strange forest 



IN THE PLANT WORLD THE ROAD RUNNER S OPPOSITE NUM- 



ber is certainly the cactus. To most people — and quite 

 properly — it is the desert plant par excellence. Many kinds 

 are, like the road runner, at home in the desert and no- 

 where else. Like the road runner also they belong to a 

 family of pioneers which moved into arid America and 

 changed itself radically to meet the new conditions. Most 

 of the cuckoo tribe live by following other habits in other 

 environments. The relatives of the desert cacti do the same. 

 Members of the Sonoran branch of the family come in all 

 shapes and sizes from tiny two-inch pincushions full of pins 



