664 MINNESOTA BOTANICAL STUDIES. 



It now remains to follow out the ecologic study begun in the 

 fifth paper of this series,* pursuing the general plan of study 

 introduced there. First of all I shall consider some of the for- 

 mations therein recorded and draw some comparisons. As in 

 the former paper I shall consider especially the more common 

 lichens, which give character to the flora and lichen formations 

 of the state. Beginning with the lichen formation of the ex- 

 posed granitic bowlders about Battle Lake, the formation may 

 be designated as follows : 



LECANORA LICHEN FORMATION OF EXPOSED GRANITIC 

 BOWLDERS (BATTLE LAKE). 



Physcia stellaris (L.) TUCK. var. apiola NYL., C. 



Physcia caesia (HOFFM.) NYL., CX. 



Placodium elegans (LINK.) DC., C. 



Placodium cinnabarrinum (Acn.) ANZ., C. 



Placodium aurantiacrm (LIGHTF.) NAEG. and HEPP., B. 



Placodium cerinum (HEDW.) NAEG. and HEPP., B. 



Placodium cerinum (HEDW.) NAEG. and HEPP. var. sideritis 

 TUCK., CX. 



Placodium vitellinum (EHRH.) NAEG. and HEPP., CX. 



Lecanora rubina (VILL.) ACH., CX. 



Lecanora muralis (SCHREB.) ScHAER.var saxicola SCHAER., C. 



Lecanora hageni ACH., C. 



Lecanora varia (EHRH.) NYL., B. 



Lecanora varia (EHRH.) NYL. var. polytropa NYL., B. 



Lecanora cinerea (L.) SOMMERF., CX. 



Lecanora calcarea (L.) SOMMERF. var. contorta FR., C. 



Lecanora xanthophana NYL., CX. 



Lecanora cervina (PERS.) NYL., C. 



Lecanora fuscata (SCHRAD.) TH. FR., C. 



Rinodina oreina (Acn.) MASS., C. 



Rinodina sophodes (Acn.) NYL., CX. 



Rinodina sophodes (AcH.) NYL. var. exigua FR., B. 



Buellia pullata TUCK., C. 



Buellia petraea (FLOT., KBR.) TUCK., CX. 



Buellia petraea (FLOT., KBR.) TUCK. var. montagnaei 

 TUCK., C. 



* Pink, B. Contributions to a Knowledge of the Lichens of Minnesota. V. 

 Lichens of the Minnesota Valley and Southwestern Minnesota. Minn. Bot. 

 Stud. 2 : 283-308. 29 D. 1899. 



