

UNIVERSITY OF CALIFORNIA PUBLICATIONS /5^^C/6>^ 



IN 



AGRICULTURAL SCIENCES CJ^\p.\ 



Vol. 3, No. 11, pp. 283-368, plates 25-42, 9 text figures April 4, 1919 



AN INVESTIGATION OF THE ABNORMAL 



SHEDDING OF YOUNG FRUITS OF THE 



WASHINGTON NAVEL ORANGE* 



BY 



J. ELIOT COTT AN-D ROBERT W. HODGSON 



Introduction 



Tlip geini.s Citrus is undonhtpdly of tropical origin. Alphonsp de 

 Candollo. aftor much investifration of liistorical and pliilological data, 

 concludes that the fcrnl range of the sweet orange is South China, 

 Cochin China, Java, and Sumatra, with a possible extension into India, 

 which regions are cla.ssed ecologically as tropical rain fore.st. ^lorpho- 

 logical evidence of the tropical origin of the orange is abundant, its 

 tropical mesopliytic nature licing indicated by glossy, broad. Ihit leaves 

 of rather loose and open cell .structure, long life of leaves, absence of 

 stoniatal devices for regulating transpiration, lack of root hairs, and 

 lack of a regular and non-interruptable period of dormancy. Living- 

 ston' ha.s recently pointed out that tlie most eificient climate for plant 

 growtli in the United States is ])eninsular or trojiical Florida. The 

 significance of this is apparent when we remember that tropical 

 Florida is the only place in the United States where the orange has 

 run wild and been able so to maintain itself. In all countries where 

 the sweet orange has nm wild after having been introduced into the 

 Xew World, such as Brazil. Paraguay, northern Argentina, and to 

 some extent in i^'lorida. the climate is distinctly tropical. 



Ilorticulturi.sts have called attention to the fact that an environ- 

 mental complex which is most efficient as regards plant growtli does 

 not nece.ssarily conduce to the production of fruit of high connncrcial 

 \aliie. (In llie otlicr hand, some rliiiialic- factors, sudi as lighl and heat, 



•Manuscript .submitted January 17, IIMS. 

 1 Physiol. Rea., vol. 1, April, 1916. 



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