8 The Principles of Fruit-growing. 



type or group of fruits ; but in general it may be 

 said that the relative annual temperature is the 

 most influential factor. 



Tlie temperature determinant. It is customary to 

 recognize three general climatal fruit -zones, the 

 temperate (typified by the apple and the peach), the 

 semi-tropical (citrous tribes, fig, olive, pomegranate), 

 and the tropical (cocoa-nut, banana, anona, mango). 

 There are no positive limits of temperature which 

 mark off or separate these zones ; but it is enough 

 for our purpose to say that the temperate zone is 

 one which is marked by a long winter of freezing 

 and by the deciduous types of fruits ; the semi- 

 tropical zone is one in which the winter is a short 

 season of light frosts or only occasional freezes, and 

 in which the fruit trees are evergreen or very nearly 

 so ; and the tropical zone is f restless, and is marked 

 by evergreen and mostly ever-growing fruit -plants. 



The limits of these climatal zones are exceedingly 

 devious. In eastern North America, the northern 

 limit of profitable fruit-growing is not far from the 

 forty -fifth parallel, and the limit sinks considerably 

 lower than this in the middle west, and rises much 

 above it on the Pacific slope. The northern limit 

 of the sub -tropical zone in the east is Northern 

 Florida and a narrow area skirting the Gulf of 

 Mexico, and upon the western side of the continent 

 it extends in the valley climates as high as the 

 fortieth parallel. The only portion of the tropical 

 fruit- zone which lies in the United States is in 

 extreme southern Florida, comprising about two 



