ECONOMIC PLANTS 253 



being set from eighteen to twenty feet apart. The 

 great peach-growing states are New Jersey, Maryland, 

 Georgia, Delaware, Michigan, Colorado, New York, 

 Connecticut, California, Oregon, and Washington. This 

 shows a wide climatic range, but peaches, owing to their 

 great susceptibility to cold, are the most uncertain 

 fruit crop raised. A few overwarm days will cause 

 the undeveloped buds to begin to swell, and then the 

 cold or frost blights them and the crop is ruined. 



Cotton and potatoes are often grown in the young 

 peach orchard in the south, the cultivation necessary 

 to these crops helping the trees. 



The peach is usually budded (see page 163) on its 

 own seedling, for the production of which the pits are 

 stratified and then planted. 



The Plum. --This tree is native in central and north- 

 ern United States, where the use of the cultivated 

 varieties for culinary purposes has much increased in 

 recent years. But we still have to rely largely upon 

 European and Japanese species for our dessert plum. 

 The production of hybrids through cross-fertilization 

 'with the foreign plums is introducing some new Ameri- 

 can types that are proving valuable. 



The American plum is the species found growing 

 wild in our woods. Nurserymen have made selections 

 from this and have developed some desirable plums. 

 Cultivation improves both the size and the quality. 



The European plum is the original plum. The more 

 common blue and yellow plum of the markets and the 

 dried prunes are from this species. It is the most 

 extensively cultivated of the plums, but is not hardy in 

 the northern Mississippi Valley. 



The Japanese plum has been widely disseminated in 



