UKITISII KOKKST TREES 187 



plains and uplands than on the higher hills. In the 

 Bavarian Alps it ascends to 2,500 feet eastwards of the 

 river Inn, and to 3,050 feet to the west of it . in the central 

 district of the Tyrolese Alps it attains an elevation of 

 3,300 feet. 



The region in which the sessile oak is indigenous corre- 

 sponds in general with the habitat of the English oak, but 

 does not extend so far to the north or east, although the 

 former is able to ascend hills and mountain slopes to a 

 greater height than the latter, viz. 320 feet higher in the 

 Harz, i, 080 feet higher in Baden, and 1,500 feet higher 

 in the southern Alps. 



In England the pedunclate oak is far more common than 

 the sessile, but in Scotland the latter species increases in 

 number. 



Tree-form and Root-system. No forest tree outrivals the 

 oak, especially the English oak, in its tendency to branch 

 formation when growing in isolated positions ; but in close 

 forest, its energy being concentrated on growth in height, 

 it develops a good, fairly straight and cylindrical, clean bole. 

 The weaker tendency to branch development in the sessile 

 oak exhibits itself in the generally straighter growth of this 

 tree in close canopy. Sufficient growing-space for the 

 development of a moderately-sized healthy crown is 

 essential for all oaks that are to be held over for the pro- 

 duction of the larger-girthed and better paid assortments of 

 timber. Otherwise, on trees being cut free from side competi- 

 tion for light and air in order to obtain large increase of 

 growth in girth and cubic contents, the bole is apt to become 

 covered with shoots (particularly in the case of the sessile 

 oak), on the adventitious buds being called into activity by 

 the increased supply of sunlight and warmth made available, 

 whilst the upper part of the crown often dies off and the 

 trees become ' stag-headed' or dry tin 



