MICHIGAN ACADEMY OF SCIENCE. 45 



TABLE VIII. — piSTRIBUTIOX OF NORTHWESTERN AMERICAN SPECIES. 



88 or 96 per cent are in common with Northeastern America. 



65 or 71 per cent are in common with Arctic Eastern America. 



57 or 62 per cent are in common with Arctic Greenland. 



60 or 65 per cent are in common with Arctic Europe. 



64 or 70 per cent are in common with Arctic Western America. 



35 or 38 per cent are in common with Arctic Asia. 



III. — MT. WASHINGTON. 



Ktaadn and Washington possess 114 species in common. The six species 

 not found on Washington are: Carex saxatalis, Carex rariflora^ Saxifraga 

 stellaris comosa, Cassandra calyculata, Carex saxatalis miliaris and Carex 

 Grahami. On the other hand it may be jjointed out that Washington 

 possesses 18 alpine species not recorded from Ktaadn -(11). While further 

 study of Ktaadn may be expected to reduce this number, yet the fact remains 

 that each of these mountains (only 161 miles apart) has its isolated peculiar 

 elements. In species conunon to both but unknown elsewhere we have 

 a striking case of relict endemism or perhaps post glacial polygenesis from 

 now extinct ancestry. Carex Grahami likewise furnishes an interesting case 

 of initial endemism apparently having here its origin, possibly as a mutant. 



IV. — THE MAIN REGION. 



Of 4he 120 alpine forms listed 64 or 53 per cent are common to the coast 

 while 36 species (30%) are found in Sphagnum Bogs (Table I). A more 

 thorough study of the bogs of the northern part of the state would surely 

 increase this latter percentage. Of the 64 coast-alpine forms 39 are to be 

 mentioned as in common with the arctics. Among the 36 bog-alpine species 

 we note 26 as occurring within the arctic realm. On the other hand the bogs 

 and coast of the .state show 30 of the.se species in common of which 22 are 

 arctic forms. 



These figures at once make clear the striking intimate relations of these 

 four habitats: mountain, coast, bog and arctic and argue physiological 

 identity which is clearly shown in the ecological similarity of the forms 

 tolerant of these habitats. An identical explanation, the glacial relict theory, 

 maj' be advanced to account for this bog-coast-alpine-arctic floristic and 

 ecological agreement. 



DISCUSSION AND SUMMARY. 



Hooker (9) has shown that arctic Europe possesses by far the richest flora, 

 some 80 per cent of the total arctic vascular flora of 797 species; while arctic 

 Asia has the poorest, only producing about 29 per cent of the arctic forms 

 and of these 29 per cent approximately 85 per cent are Arctic European. 

 Of the 67 Ktaadn species in common with arctic Europe only 24 (or 509c) 

 are known in arctic Asia, while of the 42 Ktaadn Asiatic forms 34 or 80 per 

 cent are common with arctic Europe. It is thus apparent that arctic Europe 

 is the main center of glacial distribution and that our Ktaadn flora shows 

 striking arctic European affinity with 56 per cent of the total species or 75 

 per cent of arctic forms in common, while Asia only shows 35 per cent or 

 46 per cent of Asiatic-Ktaadn forms. 



It also seems apparent that from this center migration possibly followed 



