420 PROCEEDINGS OF THE ACADEMY OF [July, 



The regions of little physiographic diversity are the following: 

 Point Pelee, Ontario, jutting into Lake Erie, comprises that part of 

 Essex County at the western end of the lake, and in the enumeration 

 of its plants those found on Pelee Island are included. Point Pelee 

 is a triangular piece of land with its acute angle running about 

 ■9 miles south into Lake Erie. About nine-tenths of this tract is 

 mostly a very wet marsh between the east and west beaches. Within 

 this marsh limit are several ponds and small lakes, while on the east 

 and . west sides are narrow low, sandy beaches, the western one 

 backed by sand dunes. Outside the marsh the land is sandy. No 

 geographic configuration could be much more simple. C. K. Dodge^ 

 has found 466 genera and 623 species of ferns and seed plants on 

 Point Pelee. The generic coefficient, which is the proportion of 

 genera to species in a flora, is for the Point flora 74.7 per cent. 



The pine-barren region of New Jersey is a country of slight relief. 

 The soil is sandy, underlaid by gravel. The streams which flow into 

 the Atlantic Ocean have nowhere a rapid current, and their mouths 

 are influenced by tide water. The hills are low, the steeper ones 

 having gradual slopes. Natural lakes are small and widely scattered. 

 The lower drainage levels are occupied by marshes and swamps. 

 With this simple topography we find a numerically poor flora of 

 250 genera and 555 species of native plants, so that the generic 

 coefficient is 45 per cent. 



Hartsville, South Carolina, the flora of which has been investigated 

 by Coker,2 is found on the inner drier part of the Atlantic coastal 

 plain. Just north of the town proper is a rapid descent of about 

 50 feet into the valley of Black Creek. This vaUey with certain 

 irregularities extends approximately one-half mile and is terminated 

 on its northern edge by sand hills, which rise in gentle undulations. 

 The general surface configuration of the country south of Black 

 Creek Valley is that of a level plain with slight elevations and depres- 

 sions, some of the latter cut by the streams. The nature of the 

 vegetation on the level plain is de-termined very largely by the 

 position of the water surface in the soil. The flora, as enumerated 

 by Coker, includes 344 genera and 628 species of plants, which gives 

 us a rather higher generic coefficient of 54.6 per cent. 



The Altamaha Grit Region of Georgia, whose flora has been 

 investigated by Harper, has fairly uniform environmental conditions. 



1 Dodge, C. K.: Annotated List of Flowering Plants and Ferns of Point 

 Pelee, Ont., and Neighboring Districts, 191-4. 



2 Coker, W. C: The Plant Life of Hartsville, S. C, 1912. 



