THE VEGETATION OF WOODLANDS. I 7 



soils do not play a great part in the surface geology of 

 Scotland, the oak-birch series of woods has a wide distribution. 

 Considerable attention has been given to the distribution of 

 the two oaks — the peduncled oak and the sessile oak. It has 

 been found that the pedunculate oak {Quercus robur or 

 pedunculata) is the more characteristic tree of southern England 

 and the Midlands, while the sessile-fruited oak i^Q. sessiliflora) 

 is more typical of northern and western England. The reason 

 for this distribution is traced to the soil, the main determining 

 factor being depth of soil. The peduncled oak is characteristic 

 of the deep-soiled clays, loams, and fine sands which are mainly 

 found in the south and in the Midlands, while the sessile oak 

 is equally characteristic of the shallow soils which prevail in 

 the north and west. So far as Scotland is concerned, we 

 have seen both oaks in the Lothians and in the Highlands, 

 but their distribution has not yet been determined. 



The distinction between these two native oaks has often 

 led to controversy, and we reproduce here some conclusions 

 taken from a recent careful analysis of the various native and 

 introduced British oaks.^ The author holds that the native 

 British oaks may all be referred to Q. sessilifiora, Q. robur 

 {pedunculata) and a hybrid between these species. Q. sessiliflora 

 is distinguished by the presence of branched stellate hairs on 

 the under surface of the leaf, and by the absence of leaf 

 auricles ; other characters, such as the length of the leaf-stalk 

 and the absence of a stalk to the acorn, are liable to variation. 

 The peduncled oak ((2- robur) has two turned-in auricles at 

 the base of the leaf-blade, and the stellate hairs are absent ; 

 the long stalk to the acorn, the very short leaf-stalk, the 

 flatter crown and the shorter bole are also characters, but 

 they are liable to considerable variation. The hybrid oak 

 has mixed characters, particularly auricles on the leaf-base 

 and stellate hairs. 



Although, generally speaking, the pedunculate oak frequents 

 deep moist soils, and the sessile oak follows the shallower 

 soils, it is not considered advisable to subdivide the oak-woods in 

 this way. The ground-vegetation is regarded as a better guide. 

 The primary division of the oak and birch series of woodlands 

 is into — (a) Oak-wood association, {b) Oak-Birch-Heath associa- 

 tion, {c) Birch-wood association. 



^ "British Oaks," by C. E. Moss, Journal of Botany, Jan. and Feb. 1910. 

 VOL. XXIV. PART I. B 



