52 VEGETATION OF THE PEAK DISTRICT [CH. 



a planted tree, it is locally abundant and succeeds well. First- 

 year seedlings of sycamore are common ; and occasionally these 

 grow up into trees. 



No species of lime is indigenous in the oak and birch woods 

 with the possible exception of the small-leaved species (Tilia 

 cordata = T. ulmifolia = T. parviflora) ; and even this is ex- 

 tremely rare. The common lime (T. europaea=T. vulgaris) 

 is never a woodland plant; and the broad-leaved lime 

 (T. platyphylla = T. grandifolia) is not indigenous in Derby- 

 shire. 



Ivy (Hedera Helix) is a constant and frequent associate in 

 all the woods. 



The ling or heather (Calluna vulgaris) is confined to 

 woods whose soil contains much acidic humus or peat, and 

 to the more open parts of such woods. 



The bilberry (Vaccinium Myrtillus) occurs in somewhat 

 similar situations to the heather, and usually grows with it ; but 

 it also thrives in more shady parts of the wood than that plant 

 (see figure 7). The cowberry (V. Vitis-idaea) is local, but 

 very abundant in some degenerate woods with a peaty soil, 

 as in Longdendale, near Crowden railway station. 



The ash (Fraxinus excelsior) is, in the oak woods, almost 

 limited to stream sides and swampy places. In the drier oak 

 woods it is very rare. 



The elder (Sambucus nigra) is locally abundant in the 

 lower woods, but rather uncommon at the higher altitudes. 

 In places where the woods are disturbed and especially near 

 villages, the plant frequently overruns the ground. 



The guelder rose (Viburnum Opulus) is, in all the damper 

 woods, an occasional associate, and reaches comparatively high 

 altitudes (about 318 m.). 



The honeysuckle (Lonicera Periclymenum) is abundant 

 and general. This plant and the ivy are the only indigenous 

 lianes of the north of England. 



