IV] GRASSLAND ASSOCIATIONS 107 



or fruit that this species becomes obtrusively conspicuous ; and, 

 at such times, it gives the tone and colour to the whole 

 association. There seems little doubt, however, that the 

 Nardus association of the Peak District is ecologically identical 

 with that of the Wicklow Hills (Pethy bridge and Praeger, 

 1905: 157) and that of the northern Pennines (Lewis, 1904 a: 

 324; 19046: 275), even though the silver hair-grass is not 

 included in the lists of these districts. 



The silver hair-grass of the hills of the Peak District 

 belongs to the form with short, wiry, and sub-squarrose leaves 

 (Deschampsia flexuosa, ? var. montana) : the form in the oak and 

 birch woods has much longer, more limp, and more slender 

 leaves. Woodhead (1906 : 383) has described and figured the 

 structural differences of some of the forms of this plant. 



The two grasses (Nardus stricta and Deschampsia flexuosa) 

 remain co-dominant up to the edge of the moorland plateau, 

 which frequently occurs at about 1500 feet (457 m.). Below 

 about 1250 feet (381 m.), the common bent-grass (Agrostis 

 vulgaris) is often an abundant associate, giving rise to a distinct 

 facies. In the late summer months, its delicate and purple 

 panicles colour the hill sides. As lower altitudes are approached, 

 this species becomes increasingly abundant at the expense of 

 the mat-grass (cf. page 112). The sheep's fescue-grass (Festuca 

 ovina) is also often associated ; and this species sometimes forms 

 plant societies and facies. 



The shaly hill-slopes of the Pendleside (or Yoredale) series 

 which encircle the upper Edale valley afford an extensive and 

 continuous expanse of Nardus pasture. On the north of this 

 upland valley are the slopes of the Peak, on the south the 

 slopes of the Mam Tor range, and on the east the slopes of the 

 Colborne moors. Such a great expanse of Nardus grassland is 

 not seen elsewhere in the district. In the sheltered Grindsbrook 

 clough, the bracken (Pteris aquilina) asserts itself very strongly: 

 the dwarf furze ( Ulex Gallii) occurs in small patches here and 

 there ; and the springs of water on the hill sides are marked by 

 clumps of the common rush (Juncus effusus). 



The last three species give to the association very different 

 aspects or facies. The bracken, where the soil is dry and the 

 locality sheltered, sometimes occurs in extensive sheets (see 

 figure 15). The gorse (Ulex Gallii) is never very prominent in 



