658 MINNESOTA BOTANICAL STUDIES. 



also selected to furnish a connecting link with the lichen flora 

 already studied farther south in the state. To ascertain the re- 

 lationship of northwestern with northeastern Minnesota, pre- 

 viously studied, as to lichen flora, two regions, Bemidji and 

 Red lake, were chosen, having an abundance of conifers and 

 swamps. These two regions lie to the north and east of the 

 others previously named and well within the pineries. It is to 

 be regretted that none of the area studied possessed rock expo- 

 sures of any sort, similar either to those in southern or in north- 

 ern and northeastern Minnesota. These have since been 

 reached in a study of the northern boundary of the state directly 

 north of the area now under consideration. 



The first area studied was that about Battle lake, about 150 

 miles northwest of Minneapolis, on the border between the 

 wooded and prairie regions. The lichen habitats here are 

 granitic and lime bowlders, earth and trees. The absence of 

 rock exposures here, as well as elsewhere in the area studied 

 during the summer, detracted much from the richness of the 

 flora. The trees in the region about Battle lake are much the 

 same as those about Minneapolis and in the portions of south- 

 western Minnesota studied in 1899. This similarity as to ar- 

 boreal flora, as well as the presence of the granitic and calcare- 

 ous bowlders gave a lichen flora quite similar to that of the 

 more southern regions named above. A careful consideration 

 of these resemblances, such as was undertaken for two regions 

 in the second paper of this series,* would of itself lead to a 

 long and laborious article, and must be omitted to give space 

 for more important ecologic considerations. A noticeable feat- 

 ure of the lichen flora about Battle lake is that nearly all the trees 

 growing lichens are common near the lakes and in heavy woods 

 back from the lakes, but rare in woods back from the lakes and 

 not heavy. All this is much like the conditions about Minne- 

 apolis, as discussed in the second paper of this series. f How- 

 ever, turning to the rocks, they were found literally covered with 

 lichens even up to the very hill-tops in the morainic area south 

 of the town. The whole number of species of lichens collected 

 about Battle lake is in. Comparing this with the numbers 



* Fink, B. Contributions to a Knowledge of the Lichens of Minnesota. II. 

 Lichens of Minneapolis and Vicinity. Minn. Bot. Stud, i : 703-716. 31 My. 

 1897. 



| Fink, B. 1. c., 705. 



