Bcrguiaii and SlaUard: climax fokmatioxs 341 



The following species of herbs are characteristic : 

 Alsine longifolia Goliiim trifiduui 



Aster paiiiculatits Men I ha eajiadoisis 



Campanula apariiwides Nauinbergia thrysiflora * 



Ciciita hnlbifcra Rimicx verticillatus 



Dryopteris thelypteris Scutellaria galericulata 



Galium, Campanula and Alsine form a ground layer under the 

 sedges and grasses, and often make very dense growths, particularly 

 the first two. 



The following species often occur with this associes, but are 

 usually not present in great number : 



Asclepias incaniata Eupatorium purpureum 



Caltha palustris Iris versicolor 



Carduus muticus Lathyrus palustris 



Comarmn palustre Menyanthes trifoliata 



Epilohium lineare Persicaria amphibia 



Equisctum fluviatile Riimc.v occidentalis 

 Eriophorum polvstachyon 



(5) Chamacdaphtic-Androvicda Associes 



The appearance of Sphagnum in pools of water between the 

 tufts of Carex is made possible by the advancing Carex which builds 

 a substratum at or above the water-level of the lake or pond. 

 Sphagnum then colonizes about the clumps of Carex or in pools of 

 shallow water between tufts. Although in Europe Sphagnum has 

 often been observed to invade open water this has not been found 

 to occur in Minnesota. The replacement of the Carex stage by the 

 bog heaths is usually attributed to an increase in the acidity of, the 

 v.-ater owing to the presence of Sphagnum, but from repeated ob- 

 servations in numerous swamps it seems that there is not a sufficient 

 increase in acidity to account for this. It is not possible at this 

 time to state the cause of the replacement of Carex by Sphagnum 

 and species of bog heaths, but in some way the reaction of the Carex 

 stage is unfavorable to its continuance while it is distinctly favor- 

 able to the development of Sphagnum. The appearance of Sphag- 

 num provides conditions suitable for the invasion of Andromeda, 

 Ledum and others of this associes. 



Consocies : The following plants are the typical consocies : 



