678 MINNESOTA BOTANICAL STUDIES. 



discussion of the Usnei formation of the pines, the plants may 

 be adapted to the coniferous wood as well as to the moist habitat, 

 it remains to be stated that the same species are both more 

 numerous and more luxuriant in the swamps than on the upland 

 pines. 



The following formation must be regarded as somewhat 

 doubtful till further studied. 



STICTA PULMONARIA LICHEN FORMATION OF CEDAR SWAMPS 



(BEMIDJI). 



Sticta pulmonaria (L.) ACH. 



Nephroma leevigatum ACH. 



Lecanora pallida (SCHREB.) SCHAER. 



Lecanora pallescens (L.) SCHAER. 



Pertusaria communis DC. 



Calicium chrysocephalum ACH. 



There is no doubt of the distinctness of the formation in 

 the region as none of the plants were found elsewhere during 

 the summer than in the cedar swamps, except the last which 

 was also found in the tamarack swamps. The plants of the 

 formation grow in dryer places in other regions and seem to be 

 as well adapted to upland woods as many other lichens recorded 

 for the tree formations of higher ground. 



The swamps afford yet one other characteristic formation 

 well developed in the area studied wherever tamaracks and 

 cedars flourish. It may appropriately be designated as follows:' 



THE CALICIUM LICHEN FORMATION OF OLD LOGS AND STUMPS IN 

 TAMARACK SWAMPS (HENNING). 



Ramalina pusilla (PREV.) TUCK., C. 



Cetraria ciliaris (Acn.) TUCK., C. 



Parmelia saxatilis (L.) FR., C. 



Cladonia mitrula TUCK., C. 



Cladonia fimbriata (L.) FR. var. tubaeformis FR., C. 



Cladonia gracilis (L.) NYL., C. 



Cladonia gracilis (L.) NYL. var. hybrida SCHAER., C. 



Calicium trichiale ACH. var. cinereum NYL., C. 



Calicium trachelinum ACH. 



Calicium sp. 



Calicium curtum TURN, and BORR. 



