50 
FOURTEENTH REPORT. 
The Phragmites-Typha Association. 
I his asociation of swamp plants occupies an extremely limited part 
ol the region. It is evidently a secondary development, following the 
clearing of bogs, which were too wet to cultivate successfully. The 
duration of this association, under present climatic conditions, provided 
ihe ground is undisturbed, could not be long because before the Typha 
is able to establish a closed association, which very nearly prohibits 
succession, the rapid ecesis of shrubs, particularly willows, but even 
tamarack and cedar, will have destroyed the identity of the association. 
Consequently the presence of this association is indicated by the pres- 
ence of Typha JatifoUa, Oxypolis rigidior and a very little Phrag mites 
com munis as relic species in some of the willow thickets, which at the 
present time occupy wet, cleared places. Ultimately the bog forest cover 
will prevail. 
As an association it is better represented in one of the treeless bogs 
northeast of Burt Lake. There a narrow belt of typically develop! 
Typha latifolm separates either the GastalicnNymphaca or the Pair pus 
ralidus from the Carex fit i for mis association. It is not unlikely that 
here the Typha invaded the tension line subsequent to the development 
of the Carex mat and the water lilies. 
The Carex filiformis Association. 
At the edge of the Castalia-Nymphaea or of the Phrar/mites-Typha 
or of the Scirpiis ralidus associations or occasionally at the edge of the 
open water occurs the Carex filiformis association, one of the most 
typical of bog associations in this part of America. The dominant 
species, growing in great luxuriance, forms large mats of vegetation 
projecting out from the shore. The long, slender leaves wave loosely 
in the wind. At a distance the upper surface appears perfectly level. 
There are virtually no other plants present in this sedge growth, ex- 
cept at the tension lines on either side. Under the mat of Carex, debris 
accumulates and builds up the bottom. Davis’s researches have shown 
that this plant is one of the most important in the formation of peat. 
In general (his association is succeeded by the Chamaedaphne caly- 
ciilota association, altlio occasionally the willow thicket may follow. 
List of the Species of the Carex filiformis Association 
DOMINANT SPECIES. 
Carex pi if or mis. 
SECONDARY SPECIES. 
Potcn t ilia pal list r is. 
Clyceria borealis. 
INVADING SPECIES. 
Chamaedaphne ealyculata. Salix lucida. 
fra fix pedicel far is. Tris versicolor. 
Sp ira ca sa li ci folia. 
