132 ANNUAL. REPORT OF THE Off. Doc. 



performing the functions of a stem. Thus it is that the potato tu- 

 ber has "eyes" or buds which are commonly borne upon stems and 

 may be used to make cuttings for propagation, just ffs the stem of 

 a grape vine or current bush may be used. As branches proceed 

 from buds on the stem, and lilcewise the large triple thorns upon 

 the honey locust proceed from buds on the stem, therefore the 

 thorns are merely transformed or deformed branches or lateral 

 stems. So, too, the tendril upon pea vines are demonstrated to be 

 modified leaves, the scales on winter buds to be deformed leaves 

 and the gorgeous and wonderful parts of flowers from the calyx to 

 the pistil are only leaves greatly changed to perform a special func- 

 tion. Facts like these, discovered only with close study and pro- 

 found reflection, help us to a clearer understanding of the principles 

 underlying our operations of pruning and training fruit trees and 

 vines. How is it that a branch of a pear tree that is a shy bearer, if 

 bowed to the ground will, in the second year, bear fruit, while the 

 uprigtit branches continue fruitless, or that the scion of a seedling 

 apple grafted on a mature tree will produce fruit buds in the second 

 year; or w^hy does a dwarf pear bear at an earlier age than a stand- 

 ard; or why will the young fruit tree injured by borers bear earlier 

 than the unharmed tree? The explanation is simple enough when 

 we know that the flower bud is only a transformed leaf bud brought 

 about by the slower movement of sap through the bent over pear 

 shoot, or the wound between the scion and stock of the apple graft, 

 or the less congenial quince stock of the dwarf pear, or the check 

 upon the growth due to the injury of insects in the trunk of the young 

 tree. 



The roots of plants as considered in modern botany perform a 

 most remarkable work in the economy of plant life, and a clear know- 

 ledge of their character and function, the length and depth to which 

 they extend themselves, has brought about many innovations in our 

 methods of cultivation. The great bulk of the material assimilated 

 to form the tissue of the plant, its leaves and fruit, must enter the 

 roots and by them be forced to the extremities of the branches. 

 In the case of an apple tree bearing 40 bushels, or a ton of fruit, not 

 only that ton, but several tons of material are gathered by the thou- 

 sands of little rootlets at the extremities of the root system. 

 Where, then, is the force by which such weights of material are raised 

 to the tops of trees? It is possessed by the roots acting like a force 

 pump with as many little valves as there are cells in their construc- 

 tion. The root pressure is exceedingly great and has been carefully 

 measured in a large variety of plants. We have seen evidencs of it 

 in the excessive flow of sap from late pruned grape vines (the bleed- 

 ing). A strong vine will in the first day after it is cut exude a quart 



