THE PEANUT {Arachis hypogaea) — ITS HISTORY, 

 HISTOLOGY, PHYSIOLOGY, AND UTILITY 



BY 



Ralph Augustus Waldron, B.S., M.S. 

 With Plates LXXIX and LXXX 



Thesis Presented to the Faculty of the Graduate School of the University of Penn- 

 sylvania, May 1918, in partial fulfilment of the requirements 

 for the degree of Doctor of Philosophy. 



CONTENTS 



Introduction •^ 



History -^ 



Introduction ■^ 



Early American Records ^°^ 



Lack of Evidence as to its extra-American Origin 3°S 



Distribution • ^ 



Recent Literature -^ 



General Morphology ^^° 



Histology -^ -^ 



Root ^^^ 



Stem ^^^ 



Leaf ^\^ 



Fruit -^^^ 



Physiology ^ 



Root Hairs ^ 



Observations and Experiments with Root Hairs 3^^ 



Absorption ■^ ^ 



Development -^ ■' 



Biological Considerations Concerning the Fruit and Gynophore 3^7 



Conclusions from Physiological Studies ^^^^ 



Uses of the Peanut ^^ 



Summary of Results 335 



Literature Cited ^•^' 



Explanation of Plates ^3 



