I. CONTRIBUTIONS TO A KNOWLEDGE OF THE 



LICHENS OF MINNESOTA III. THE ROCK 



LICHENS OF TAYLORS FALLS. 



BRUCE FINK. 



THE COMPOSITION AND ORIGIN OF THE FLORA. 



The lichens listed in this paper were collected during two reg- 

 ular annual excursions of the Summer School of the University 

 of Minnesota. The date of collection of all numbers up to 92 

 is August 15, 1896, and the plants were collected by Professor 

 Conway MacMillan and the writer, on the Algonkian igneous 

 rocks of the Interstate Park, or on earth or branches in the 

 crevices of the rocks. On the I4th of August, 1897, I accom- 

 panied another excursion to examine the lichens growing on the 

 Cambrian sandstone exposures near the park. Numbers 93 to 

 119 were collected by me during this second trip, and more spe- 

 cies were noted on the sandstone, which had been collected the 

 year before on the igneous rocks. In all, 24 lichens were found 

 growing on both sandstone and igneous rocks, 22 on the igne- 

 ous rocks only, 20 on the sandstone only, 10 on earth in the 

 crevices of the igneous rocks and 2 on roots or branches in the 

 crevices. The last lichen of the list was found on old boards 

 and is recorded here because rare or difficult to detect and new 

 to the State. 



It was my intention when I went to the park to publish what- 

 ever might be found of interest with the last number of this ser- 

 ies of papers. But after observing the field it became apparent 

 that the locality is one of great interest both as to origin and 

 present composition of its lichen flora and that these character- 

 istic floral features could be presented best in a separate paper. 

 A little observation showed that the tree lichens do not differ to 

 any noticeable extent from those about Minneapolis, and I con- 

 sequently confined my collecting to the igneous rocks and 



