﻿494 BOTANICAL GAZETTE [june 



of Car ex nigricans, which increase in size as we recede from the 

 snow until they form a continuous ground covering. Thus far 

 the succession is invariable; but the plants that grow in scattered 

 groups in the stretches of Carex nigricans at some distance from the 

 snow patches may be Carex invisa, Epilobium latifolium, Petasites 

 frigida, Caltha Macounii, Oxyria digyna, Parnassia parviflora, or a 

 Ranunculus. When one or more of these plants have joined 

 Carex nigricans, conditions no longer warrant the designation of 

 ' ' desert" to this association, but it merges into the hydrophytic 

 or hydromesophytic group, for moisture from the melting snow 

 patches is, of course, abundant in these situations. The term 

 "desert" as applied to the fungus-moss-sedge association bears with 

 it none of the usual suggestions of dryness and heat, but, on the 

 contrary, connotes abundant moisture but physiological dryness 

 due to extreme cold. It is to be remembered in this connection 

 that the suffocating action of the snow, previously mentioned, is 

 here a potent cause of the poverty of plant life. 



