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.t| 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 111. 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. 1: 703-716. 31 My. 
1897. 
(epi Be lcs. 705. 
