1022 MINNESOTA BOTANICAL STUDIES. 



becomes important as the lake is approached. A grouping of 

 the humus plants into those which can endure the strong illu- 

 mination near the edge of the Betula wood, for example, and those 

 which must have the deeper shade is effected, giving rise to a 

 rudimentary zonal arrangement even here. Moneses is so essenti- 

 ally a shade loving plant (ombrophile) that it does not approach 

 the edge of the wood, but remains in the deep shadows. Cor- 

 allorhiza, on the other hand, prefers a station nearer the edge. 

 Comparative tests of the different humus plants with reference 

 to their degree of ombrophilic instinct would be useful, and 

 could be made in such a region. 



CONCLUSION. 



The principal formations as studied at Lake of the Woods, 

 have now been passed in review and their characters noted and 

 commented upon. No extended summing up is necessary for 

 it must be apparent that the purpose of the paper has been but 

 a single one — to point out the dependence over such an area as 

 the shores of the lake, of plant formations upon topographic 

 and environmental conditions. It has been shown how each 

 formation may be explained briefly as connected with a certain 

 melange of outward conditions, and an effort has been made to 

 analyze these conditions both by themselves and as connected 

 with the growth of vegetation. Such an account, the first of 

 its kind published in America, may be of service in stimulat- 

 ing ecologic study of plants, and if it be so fortunate its author 

 will be well satisfied and repaid for some months of arduous 

 work in the field. There is no question that the study of plant 

 distribution over limited areas must be pursued more labori- 

 ously than ever, if the large problems of distribution are to re- 

 ceive accurate and authentic solution. Ecological distribution 

 as a field of botanical research needs many students.' 



