
PLANE ASSOGIATIONS = = Oy, 
the fact that the period of cross-pollination is so short that | 
- without brilliant colouring insects might not be attracted. 
Alpine plants are xerophytic in character; the leaves are 
often covered with hairs, giving them the silvery white colour 
so well known in the Edelweiss. It is interesting to compare 
alpine species with the corresponding lowland form ; thus the 
alpine species of Lady’s Mantle (Alchemilla alpina) has this 
dense covering of hairs, which is absent from the common 
lowland form, Alchemilla vulgaris. 
Moorland Moors vary not only as regards soil, but, above 
Vegetation. al], in the amount of water present in the soil. 
On these two factors it largely depends what dominant forms 
are present. The moorland of the West Riding of Yorkshire 
has been thus arranged by Dr. William G. Smith and Mr. C. E. 
Moss : 
(a) Cotton-grass moor, called ‘moss moor,” from the fact 
that the bog-moss Sphagnum usually forms (although it is 
not so conspicuous in Yorkshire) an important constituent of 
the peat. This “moss moor” is practically a bog. 
(0) Heath moor. 
(c) Rough-grass moor. 
In Yorkshire the cotton-grass moors extend for miles ; they 
require a permanently wet soil, with a rainfall of at least 
40 inches. The flowering plants are very few. The Bilberry 
(Vaccinium) and a few heaths are the most abundant. Bog- 
asphodel and Sundews are rare. It is interesting to notice 
the struggle that is going on between the Bilberry and the 
Cotton-grass; where the moor is wind-swept and drier the 
Bilberry ousts the Cotton-grass, and becomes the dominant 
form. It should be noted that heather is scarce in a cotton- 
grass moor. 
The Heath or Heather moor is far drier, and requires a 
better drainage than the moss moor. It occurs on the edges 
of the latter, and in patches. The plants forming the Heather 
moor association are far more numerous than those of the 
Cotton-grags ; furze and broom may be mentioned, also several 
sedges and grasses, 
a 
