II] WOODLAND ASSOCIATIONS 65 



all probability, either been planted, or they are the descendants 

 of planted trees. The latter is much the more rare occurrence, 

 as few pine seedlings are met with in this district. 



ASH WOODS OF FRAXINUS EXCELSIOR 



Ash woods are characteristic of the slopes of the limestone 

 hills of the west and north of England. In previous British 

 vegetation memoirs, woods of this type have been described on 

 the limestone of the mid-Pennines (Smith and Rankin, 1903), 

 in Westmorland (Lewis, 1904 a), and in Somerset (Moss, 1907 a). 

 They do not appear to have been described by continental plant 

 geographers. Smith and Rankin (1903 : 168 et seq.) mentioned 

 three sub-types. The first of these, which they termed " scar 

 woods," occurs on the slopes of hills of the Carboniferous Lime- 

 stone : such " scar woods " are more of the nature of scrub than 

 of woodland. "The hazel [Corylus Avellana] is the dominant 

 element most commonly found ; but the ash [Fraxinus excelsior] 

 occurs frequently, and sometimes close enough to reduce the 

 hazel to a subdominant form.... As a rule, the ash occurs but 

 sparingly, because, being almost the only timber tree in the 

 limestone dales, it is generally removed. In this district, few 

 of the woods receive any attention ; and little is done to check 

 disforesting. Almost all the scar woods are therefore to be 

 regarded as shrubby thickets " [i.e., as scrub]. These ash and 

 hazel scrubs are interesting in that they still furnish the habitat 

 of that rare British orchid, the lady's slipper (Cypripedium 

 Calceolus). The second sub- type mentioned by Smith and 

 Rankin occurs at lower levels on the Permian or Magnesian 

 Limestone and in the bottoms of the dales of the Carboniferous 

 Limestone, and consists of ash woods which have been much 

 altered by planting beech, oak, sycamore, pine, and larch. 

 The third sub-type is termed a " hazel copse of the Permian," 

 and is made up of scrub occurring on the Permian limestone. 

 Lewis gives only a brief account of the woods of the district 

 which he investigated; and it is not easy to relate them to 

 general woodland types. However, the "birch woods" men- 

 tioned by him (1904 a: 319), judging from their occurrence at 

 comparatively high altitudes on limestone and from the list of 

 associated species, would appear to belong to the general ash 



