SUDAN GRASS AND RELATED PLANTS. 



shown in figure 4. Attempts to cross these two species artificially in 

 the greenhouse have been successful in only a very small percentage 

 of the trials, most of the attempts resulting in failure even under fa- 



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AFRICA 



© JOHNSO/V GRASS 

 GRASS SORGHL/MS 



Fig. 3. — The natural distribution of Johnson grass and the grass sorghums. 



vorable conditions. There is apparently an antagonism or unfavor- 

 able reaction between the reproductive organs of these two plants, 

 which is rather decided evidence of their specific differences. 



