PROFITABLE TIMBER TREES 67 



form crowns above them which check their upward growth 

 and prevent undue encroachment upon these leaders of the 

 group. The stems of these latter are thus gradually drawn 

 up and shaded by their own kind until the smaller indi- 

 viduals no longer compete with them, and they are then 

 able to develop their crowns unchecked, and add bulk to 

 the stem which has attained height under such conditions. 

 Such conditions are very difficult to secure ia ordinary 

 plantations, but are possible in coppices which ignore that 

 regular distribution of age classes which constitute the 

 ideal of the orthodox forester, or in woods worked on the 

 uneven-aged group system ; and where we have the requisite 

 soil, climate, and situation, the cultivation of oak in some 

 such manner may be accomplished with success. 



The Sessile-Flowered Oak (Q. sessiliflora). 



Although this sub-species of the British oak has never 

 received any different treatment from the pedunculate 

 variety in English forestry, there can be little doubt that 

 its physiological peculiarities entitle it to be treated as a 

 distinct species in sylvicultural operations. Botanists have 

 always recognised its distinct type of inflorescence, shape 

 of leaf, and so on ; but there the distinction stops, and it 

 is left for the forester to note the more important differences 

 which affect the economic values of the two species. The 

 botanical characteristics of the tree, which differ from 

 pedunculata, are chiefly the sessile flower on the axis of 

 inflorescence, the long footstalk to the leaf, and the wedge- 

 shaped base of the latter. These characteristics are always 

 present in the true sessile-flowered type; but there exist 

 a great number of individuals which exhibit a more or less 

 intermediate stage — probably the result of cross-fertilisation. 

 This has led many, whose knowledge of forestry is more or 

 less limited, to the belief that the two trees are simply 

 extreme types of different varieties of the same species, and 

 it is certainly a fact that the mere botanical examination 

 of the trees gives a good deal of colour to this theory. But 

 when we come to their habits of growth and behaviour under 



