BOTANICAL CHARACTERS 



n 



if it has only one or two leaves, and these are eaten off CHAP, 

 by a caterpillar, the plant will suffer more than when it has 

 six leaves, some of which will be able to function and repair 

 the damage done while the others are being devoured. If the 

 root-system only penetrates to a depth of 2 or 3 inches, 

 the young plant is more likely to suffer from a temporary 

 drought than if its roots are tapping, a supply of soil moisture 

 at a greater depth. It is highly desirable, therefore, that the 

 seedling should be encouraged to get beyond this critical 



Fig. 17. — Maize-grains planted upside down, showing geotropism of the 

 root and apogeotropism of the shoot. 



stage as quickly as possible ; this is one important reason for 

 the use of artificial fertilizers in South Africa (chap. VIII.). 



After the seedling has developed a root- and leaf-system of 

 its own (Fig. 18), growth is rapid if suitable conditions prevail. 

 Conditions favourable to rapid growth include warmth and 

 moisture of the soil, sunshine, and a suitable tilth of soil to 

 prevent water-logging. At the Geneva (New York, U.S.A.) 

 Experiment Station, growth of the maize plant has been 

 measured and found to range from 3 to 1 8-J- inches per week; 



