CHAPTER II. 

 CITRUS RELATIONSHIPS. 



The family Rutaceae, to which the citrus fruits belong, 

 is represented in the United States by the prickly ash 

 (Xanthoxyluin), hop-tree (Ptelea), torch-wood (Amyris). 

 and a few other plants. Though comparatively few mem- 

 bers of the family are found in the temperate and sub- 

 tropical regions of North America, this does not mean 

 that there are not many others in different parts of the 

 world. 



The representatives of the family are mostly tropical 

 in their distribution, being found in tropical Africa, south- 

 eastern Asia and Australia, numbering in all upwards of 

 nine hundred species. Hooker in his Flora of India, 1875. 

 gives twenty-three genera, with at least seventy-eight 

 species native of that country. 



Some writers have referred to some of the citrus fruits 

 as being native in Florida, and the fact that lemons, limes 

 and oranges have become thoroughly naturalized and now 

 grow side by side with native trees in the hammocks or 

 forests, lends color to the belief that they are indigenous. 

 But, on the other hand, we know that they are of Spanish 

 introduction, and no citrus trees were growing in the 

 peninsula before the advent of Europeans. This is a. mat- 

 ter of history. No species of citrus is native of America, 

 and neither are any members of closely related genera 

 indigenous on the American continent. 



In classifying the genera of the family Rutacese, some 

 authors have placed the citrus between Atlantia and Fe~ 

 ronia, but the more recent classifications place citrus as 



