BOTANICAL CHARACTERS 7S 



Changed into the various compounds on which the plant lives chap 

 and grows. The plant gets most of the elementary constitu- IV - 

 ents of its food in this way. 



Maize is a surface-rooting plant. The majority of its 

 permanent roots usually start at about i inch below the sur- 

 face of the soil, regardless of the depth of planting (Hunt, 

 0- The general tendency of the roots is to spread horizon- 

 tally, near the surface, for i or 2 feet all round, and then 

 to turn abruptly downward. As a rule the horizontal roots 

 occur within 4 inches of the surface. Hunt (1) found that 

 in young plants one to six weeks old, by far the largest part 

 of the root-system occurred at a depth of 2 to 4 inches 

 from the surface. He concludes that the distribution of the 

 roots is probably dependent more upon a proper supply of 

 oxygen and water than upon temperature of the soil. 



Maize roots have been measured 8 feet in length (not 

 depth). They have been traced to a depth of 4 feet and 

 slightly over, but as a rule most of the root-mass occurs within 

 the first 2 feet of soil. The following measurements have 

 been recorded : — 



Height of plant J inch, root S inches long. 

 ,1 ,, 3 inches, root 13 inches long. 



,> ,, 5 inches, root ir to 24 inches long. 



The joints (nodes) at the lower portion of the stem, above 

 the surface of the soil, are often provided with roots, few or 

 many in number, called adventitious or "brace-roots" (Fig. 

 23), some of which grow downward till they reach the soil, 

 and then appear to assist in anchoring the plant. These ad- 

 ventitious roots are more plentiful in some of the less improved 

 Tropical American breeds (e.g. Cusco, Mexican, etc.) than in 

 many of the more highly-bred North American sorts. In 

 some breeds they occur at a considerable distance up the stem ; 

 it seems probable that in such cases the plants are accustomed 

 to grow on river banks, subject to floods which earn' a deep 

 deposit of river mud, and into which the " brace-roots " may 

 penetrate. 



From the above description of the root-system we draw the 

 following conclusions : First, that the maize plant being a sur- 

 face feeder requires that its food supply shall be within a short 



