DECORATIVE TREATMENT OF THE PINETUM. 281 



Pruning of Pines. — The fir tribe^ when grown in close 

 plantations^, require little or no pruning. • In the Pine- 

 tunij a moderate application of the knife is beneficial to 

 many of the species. Owing to difierences of climate, 

 or variation in the pressure of the atmosphere from dif- 

 ferences of altitude, some of the sorts, which are tail 

 trees in their own comitries, are apt to grow bushy with 

 us ; or, from accidental circumstances, some of the 

 higher lateral branches may show a disposition to com- 

 pete with the leading shoot. In aU these cases the thin- 

 ning out of the branches, especially the small ones, and 

 the foreshortening of those which are acquiring an ex- 

 cessive or irregular luxuriance, will be found useful, par- 

 ticularly in the Cedrus, Picea, and Abies groups. The 

 object kept in view should be to direct the flow of sap 

 to the head and shoulders of the tree ; but it ought to 

 be regarded as a first principle, that, by pruning, the na- 

 tural form of growth is to be promoted, and not con- 

 strained into anything artificial. Mr. M'Nab, of the 

 Edinburgh Botanic Garden, who has inherited and ac- 

 quired much experimental knowledge in this department 

 of arboriculture, has found that the pruning of trees 

 in the Pinetum is most successfully performed in July. 

 This result indicates that the proper time for this work 

 is when, the season^s growth being far advanced, and 

 the flow of sap abated, there is little danger of an ex- 

 cessive exudation of resinous matter from the wounds. 

 We may add, that it is generally inexpedient to take ofi" 

 large limbs from this class of trees. 



Decorative treatment of the Pinetum. — The Pinetum 

 when planted separately, as it is desirable it should be, 

 is best arranged in groups with irregular lawns passing 

 between them ; — the larger trees occupying the leading 



