iJTRUCTURB OF MAIZE 



139 



for fodder purposes, and gama grass {Tripsacum dactyloidcs 

 L.) which was a rather conspicuous feature of the native herbage 

 of the prairie regions in the central and southern 

 portions of the United States. 



The wild protot}^e of Zea has not with cer- 

 tainty been identified. So far as known there is 

 only the one species which includes all the culti- 

 vated t}'pes and varieties of maize.^ 



209. Roots. — The fonn and habit of gro^^th 

 of the roots of maize are similar to those of 

 wheat, although modified somewhat in position, 

 due doubtless to the plant being in hills or drills 

 instead of being broadcast. The general tendency 

 is for the roots to grow somewhat horizontally for 

 one or two feet and then turn down more or less 

 abruptly. The position of the roots is modified 

 by the depth of fertile soil and by depth to which 

 the seed bed has been stirred.^ The indications 

 are that the distribution of roots depends more 

 upon a proper supply of ox}'gen and water than 

 upon temperature. The following table shows a Brace roots on Mex. 

 number of roots at six inches from the plant at l?"ioTa'^stlti^n 

 different depths in plants one to six weeks old as farm (after King). 

 examined in a black prairie soil at the Illinois Station : 



I For a summary of the evidence concerning the wild protot3-pe of maize, see 

 Maize: A Botanical and Economic Study. By John W. Harshberger. Contribu- 

 tions from the Botanical Laboratory of the University of Pennsylvania, VoL i, No 2. 



• N. Y. State (Geneva) Rpt. 1SS7, p. q5 ; iSSS, p. 171. 



