616 



METASPERMAE OP THE MINNESOTA VALLEY. 



I. EXAMINATION OF FAMILIES REPRESENTED IN THE 

 MINNESOTA VALLEY. 



The total number of families represented by the metasper- 

 mic plaijt-population of the Minnesota valley is 106. Accord- 

 ing tD Engler and Prantl, the total number of metaspermic 

 families in the world is 222. Thus 48.0 per cent, of all the 

 families in the world are represented within the region of 

 our study. Of the 106 families, 21 are Monocotyledones, 60 

 are Archichlamydeae, and 25 are Metachlamydese. The total 

 number of monocotyledonous families is 43, of Archichlamydeae, 

 131. and of Metachlamydeae, 48. Thus there are in the Min- 

 nesota valley, 48.8 per cent, of all monocotyledonous families, 

 45.7 per cent, of all archichlamydeous and 52.0 per cent, of all 

 metachlamydeous families. Of all families in the valley, 19.8 

 p?r cent, are Monocotyledones, 56.6 per cent, are Archichla- 

 mydeae and 23. 5 per cent, are Metachlamydeas. These facts 

 are condensed into the following table: 



Not all of these families are equally distributed over the 

 world. Some are much more limited in their range than 

 others. An examination of the general range of the 106 

 families represented in the valley of the Minnesota shows that 

 they may be divided, according to their range into, six groups 

 as follows: 



A. Cosmopolitan families. 



B. Extratropical families. 



C. Tropical and subtropical families. 



D. Northern extratropical families. 



E. Western Hemisphere families. 



F. North American families. 



