Mar. 1911.| BOTANICAL SOCIETY OF EDINBURGH 153 
distinct variety, viz. the shortness of the sward and the 
absence of tall Dicotyledons as a rule. The central type, on 
the other hand, may have several storeys of vegetation. 
2. Nardus-Carex association.—Here also there are the 
two types “rich” and “poor.” In the first case Curex 
flava is perhaps most characteristic; in the second the 
glaucous sedges, as before. 
Perhaps in both cases the soil is more peaty than in the 
Agrosto-Caricetum, but is never so wet as the latter some- 
times is. The tendency is to pass into heath, and this is 
forecasted even in the moistest conditions in the character- 
istic abundance of Scabiosa succisa. 
The panicea variety often occurs in tussock form, 
Nardus dominating on the little hummocks, and the 
glaucous sedges on ground between them. 
3. Aira ceespitosa association.—This is one of the tussock 
forms previously discussed, which may occur as an almost 
pure association, but more commonly interspersed through- 
out some other association. The intervening vegetation 
may vary widely in character, from semi-aquatic, with 
Menyanthes and the like, to apparently dry pasture. Aira 
appears, however, to depend on a wet subsoil, and it is a 
common sight in some districts to see good pasture ground, 
in need of drainage, becoming worthless through the en- 
croachments of this useless plant. The soil characters of 
this association place it rather in sub-formation 2, but it 
scarcely seems worth while detaching it from the allied 
associations that follow. 
4. Juncus conglomeratus cussociation. — Juncus re- 
sembles Aira ceespitosa in forming tufts, but does not rise 
into tussocks as the latter sometimes does. Abundance 
of Juncus tufts is specially characteristic of wet ground 
which has once been cultivated but allowed to lhe 
fallow for some time—i.ec. as a retrogressive association. 
After many years plants of peat moor and moist heath 
begin to appear, such as Eriophorum angustifolium, 
Calluna, Erica, ete., but this is rarely allowed to happen. 
A Juncus association is also the most frequent in the 
station deseribed as “ wet springy hollows.” In this situa- 
tion it is a natural product. 
5. Iris association.—Like Juncus conglomeratus, Iris 
