SOIL AND SUBSOIL. 



173 



poorly cultivated ; and it frequently matures a crop without the 

 aid of a single shower after planting. See figures 33, 34. 



The annexed plate (No. 32) shows the main roots ,of two 

 native perennial weeds of California, the goosefoot (Cheno- 

 podium calif ornicum) and the figwort (Scrophularia cali- 

 fornica), common on the lower slopes of the coast ranges. The 

 soil was a heavy clay loam or " black adobe " resulting from 

 the weathering of the clay shale bedrock, fragments of which 

 are so abundantly intermixed with the substrata that excava- 

 tion of the roots became very difficult. Yet the main root of 

 the goosefoot went down below the depth of eleven feet. 



The main root of the figwort, also, was followed below the 

 depth of ten feet without reaching the extreme end. This 

 proves clearly that the great penetration of the goosefoot was 

 not, as might be supposed, due to its bulbous root. Yet such 

 thickening of the root just below the crown is a rather common 

 feature in arid-region plants, and can here be noted even in the 

 figwort, within whose botanical relationship bulbous roots are 

 almost unknown. 



Any one accustomed to the cornfields of the Middle West, 

 where in the after-cultivation of maize it is necessary to re- 

 strict very carefully the depth of tillage to avoid bringing up a 

 mat of white, fibrous roots, will be at once impressed with the 

 remarkable adaptability of maize to different climatic condi- 

 tions, as exhibited in such cases and shown in figures 33, 34. 

 In southern California, in the deep mesa or bench soils, corn 

 stalks so tall that a man standing on horseback can barely reach 

 the tassel, and with two or three large ears, are quite com- 

 monly grown under similar rainfall-conditions. 



Importance of proper Substrata in the Arid Region. The 

 paramount need of deep penetration of roots in the arid region 

 renders the substrata below the range of what is usually under- 

 stood by subsoil in the humid climates, of exceptional import- 

 ance. A good farmer anywhere will examine the subsoil to 

 the depth of two feet before investing in land: but more than 

 this is necessary in the arid region, where the surface soil is 

 often almost thrown out of action during the greater part of 

 the growing season, while the needful moisture and nourish- 

 ment must be whollv drawn from the subsoil and substrata; 



