LETTER OF TRANSMITTAL. 



U. S. Department of Agriculture, 



Bureau of Plant Industry, 



Office of the Chief, 

 Washington, B.C., July 3, 1911. 

 Sir : I have the honor to transmit herewith and to recommend for 

 publication as Bulletin No. 229 of the series of this Bureau the accom- 

 panying manuscript, entitled "Agricultural Varieties of the Cowpea 

 and Immediately Related Species." This paper has been prepared 

 by Prof. C. V. Piper, Agrostologist in Charge of Forage-Crop 

 Investigations. 



The cowpea is now the most important legume grown in the cotton 

 States. At the present time about 15 varieties of this crop are in 

 common cultivation in these States. The varieties grown in a small 

 way number perhaps twice as many more. Owing to the fact that 

 the seed is still largely hand picked, the tendency is for whatever 

 variety was first introduced in a locality to persist. The increased 

 commercial handling of cowpea seed in recent years has to a consid- 

 erable extent changed this condition of affairs, but varieties of relative 

 inferiority are still too largely grown. 



In investigating the varieties of cowpeas the effort has been made, 

 with the assistance of the Office of Seed and Plant Introduction, to 

 obtain as many as possible of the existent varieties from all parts 

 of the world, so that a comprehensive idea of them could be obtained 

 with the end in view of determining which are most valuable. In 

 this collection are also included many varieties of the closely related 

 species, the asparagus bean and the catjang. While it is very certain 

 that the list of varieties that have been brought together for com- 

 parison and study is far from exhaustive, yet it is believed that the 

 series is sufficiently complete to exhibit all of the characteristics which 

 occur in this group of plants that are likely to be of value either 

 directly or to the plant breeder. 



On account of the importance of the cowpea various extensive 

 investigations of the crop have been undertaken by this Bureau. The 

 present bulletin presents the results obtained by a comprehensive 



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