Elgee : ' SxHddeJis ' in North-East Yorkshire. 19 



edges with young Erica cincrca and Tctralix prevailing in the 

 centre. 



On peaty moors, Calluna and the Bilberry {\'accinium 

 Myrtilliis) are the chief features of the vegetation. Conse- 

 quently, whenever the moor is burnt, Bilberry quickly occupies 

 the Swiddens owing to its more rapid growth. This was par- 

 ticularly noticeable on Glaisdale Ridge, where there are several 

 Swiddens covered exclusively with Bilberry. Another had a 

 little Callitna mixed with it, and in one place supported Bracken 

 though this plant does not grow in the immediate vicinity. 



On southern slopes the burning of the vegetation gives 

 Bilberry a strong hold. Thus on the south side of Baysdale, 

 Bilberry Swiddens are frequent, whilst in Stockdale a similar 

 slope is clothed with Bracken in the lower parts, immediately 

 succeeded by great spreads of Bilberry on the burnt areas of the 

 higher parts. This plant is very partial to slopes, particularly 

 those facing the north. I have not yet been able to ascertain 

 whether it is ousted in time by either Heather or Bracken. 



The Bracken also is essentially a plant of the moorland 

 slopes of North East Yorkshire, and often enters into strong 

 competition with Calhina. Where the slopes are burnt, it at 

 once spreads on to the Swiddens, and the Heather rarely or 

 never returns. This is well shewn in many localities. The 

 moors at the end of the ridges dividing the northern dales 

 present a mixed vegetation, and in the case of Danby Ridge, 

 this consists essentially of Calluna and Mat Grass [Nardus 

 stricta), interspersed with the Crowberry [Empetnim nigrum), 

 the Bilberry, and bushes of Gorse. Here the Swiddens of the 

 slopes are frequently covered with Bracken. In Baysdale, 

 incautious firing has converted good moorland into almost 

 nothing else but Bracken. 



On Danby Ridge, but at a greater altitude than in the cases 

 just noticed, pure Heather moor comes in, and a remarkable 

 Swidden of a somewhat rare type was observed here, the ^•egeta- 

 tion being in such marked contrast to that of the surrounding 

 moor. The Swidden shewed innumerable clumps of Empctrum 

 nigrum interspersed with large spreads of the Sheep's Sorrel 

 {Rumex Acetosella). Bilberry occurred sporadically amongst 

 the Crowberry, as v\'ell as Calhina and J uncus squarrosus between 

 the clumps of Crowberry. This Swidden, which stood on fiat 

 ground, terminated on one side in a very strong Bilberry and 

 Bracken slope, and there was a noteworthy absence of Bracken 



1910 Jan. I. 



