PRUJS'IXG FOREST TREES. 69 



are our object, instead of low and very stocky ones. 

 Trees growing in an open field and left to themselves, will 

 usually have branches sufficient to shade their stems. 

 This appears to be not only natural, but beneficial, for 

 when the stem is fully exposed to the sun, the bark be- 

 comes dry and hot, and the flow of sap is retarded in its 

 movements. It is only, however, while the trees are 

 young and the bark thin, that any particular injury will 

 be perceived. 



When the trees are raised in nurseries, the stems are 

 partially shaded ; consequently the lower branches are 

 not required for shade, but only to assist growth until a 

 sufficient number of others have been produced, and then 

 their service may be dispensed with without injury to 

 the tree. 



Trees standing singly and alone where they have room 

 for full development, should have at least two-thirds of 

 tlieir hight occupied with branches, but where grown in 

 forests for timber, the rule may be reversed, although we 

 may vary the proportion of occupied and naked stem, ac- 

 cording to the natural habit of the tree. The pruning 

 of forest trees should not cease with their final planting 

 in the position in which they are to remain, because an 

 occasional lopping off of a branch here and there, removal 

 of sprouts from near their base, or suckers sj)ringing 

 from roots, may assist greatly in kee2)ing them in good 

 shape, and prevent the growth of parts not desired. 

 Stunted, distorted specimens, may often be entirely ren- 

 ovated, as it were, by judicious pruning. 



TIME TO PRUNE. 



This is a subject which has l)een frequently discussed 

 among arboriculturists, and all who cultivate trees of 

 any kind, but all will agree that it should never be done 

 at a time when the sap will flow from the wound, as this 

 not only causes a loss to the tree, but the slowly oozing 



