94 VEGETATION OF THE PEAK DISTRICT [CH. 
is a very thin forest of more or less dwarfed and stunted trees. 
In nearly all cases, however, the scrub of this district appears 
to consist of retrogressive forest communities, and only rarely, 
as, for example, on certain fresh and newly formed soils beneath 
cliffs, of scrub progressing towards mature woodland. In the 
retrogressive scrub, a number of the more hardy ground species 
of woods still persist, such as the wood-rush (Luzula pilosa), the 
wood vetch (Vicia sepium), Lathyrus montanum, the wood violet 
(Viola Riviniana), the cow-wheat (Melampyrum montanum), 
and the ubiquitous bracken (Pteris aquilina); but their 
ultimate extinction, except perhaps in the case of the bracken, 
as the woodland or scrub vegetation degenerates still further 
towards grassland or heath or moor, appears certain. 
Several of these areas still retain the place-name “wood,” 
although now the name is most inappropriate; but as such 
areas occur within the primitive woodland zone, on more or 
less sheltered slopes often near the head of the cloughs 
(cf. figure 12) and dales (cf. figure 13), there need be no doubt 
that the place-name really indicates the former nature of the 
vegetation. It would appear to be true that, in districts which 
are capable on climatic and edaphic grounds of supporting 
woodland or true forest, the majority of the examples of open 
scrub are to be regarded as degenerate woods and as retro- 
gressive associations. A study of numerous examples of such 
associations leads to the conclusion that the following succes- 
sions have occurred and are still occurring in this district: 
Succession I Succession II Succession III Succession IV 
Oak and birch | Oak and birch| Oak and birch Ash woods on 
woods on sand-| woods on rocky | woods on steep || limestone slopes 
stone plateaux sandstone slopes | shaly slopes 
Scrub Scrub Scrub Scrub 
Siliceous grass- | Siliceous grass- | Siliceous grass- Calcareous 
land and heather | land (with Mo- | land grassland 
linia) 
! ! 
Moors Moors 
