LUTHER BURBANK 



It is only in very recent years that California 

 fruit has challenged the product of the Spanish 

 orchards. 



The absorption of water by the roots of the 

 tree, and its elevation through the trunk to supply 

 the deficit made by constant transpiration from 

 the pores of the leaves is a phenomenon that has 

 been perfectly familiar to botanists for a long 

 time. It was demonstrated experimentally by 

 Stephen Hales early in the 18th century. But the 

 forces that lie back of the phenomenon have been 

 very little understood. 



Very recently one of the most celebrated 

 American botanists has declared that the cause of 

 the rise of sap in trees remains perhaps the most 

 interesting of botanical puzzles. 



It is, in effect, as some one has pointed out, a 

 case of water running up hill, and many botanists 

 have found it mystifying that the plant tissues are 

 able to withstand the pressure that a column of 

 water must exert, particularly in the case of tall 

 trees. 



THE RISE OF SAP IN THE TREE 



In point of fact, however, it should be recalled 

 that the sap in the tree is not carried in open tubes 

 comparable to the arteries of the animal system. 



If it were in such tubes, doubtless no plant 

 tissues could withstand the pressure that would be 



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