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quite variable and in this treatment var. alpinus includes 

 vars. borealis , f iliformis and macounii of Fernald (1950). The 

 larger-leaved plants reported by Hellquist (1975) as var. 

 macounii appear to be var. alpinus as treated by Cronquist et 

 al . (1977). Range extends from Greenland west to Alaska, south 

 to northern New England, New York eastern Pennsylvania, 

 Colorado, and Utah. 



Rare and endangered plant lists: Maine, New Hampshire 



alkalinity: mean 66.0 mg/1; range 24.0-88.0 mg/1 

 pH: mean 7.8; range 7.3-9.1 



5. Potamogeton bicupulatus Fernald Fig. 6, Map 6 



Abundant in acid waters along the coastal plain of New 

 England. This species was treated as P_^ capillaceus Poir. in 

 Fernald (1932, 1950) but Reznicek and Bobette (1976) refer it to 

 P. bicupulatus in their treatment of section Hybridi . Range 

 extends from Maine west to scattered locations in Michigan and 

 Wisconsin, south to New Jersey, New York, Pennsylvania, Ohio, 

 and northern Indiana; most abundant in New England. 



alkalinity: mean 6.4 mg/1; range 1.5-21.0 mg/1 

 pH: mean 6.4; range 5.4-7.2 



6. Potamogeton spir illus Tuckerman Fig. 7, Map 7 



Abundant in acid to moderately alkaline waters 

 throughout New England. This species is sometimes confused with 

 P. bicupulatus and P^ diversifolius . Plants are often found 

 without floating leaves, but abundant fruit makes identification 

 easy. Range extends from isolated locations in Newfoundland 

 west to isolated sites in South Dakota, south to Delaware, 

 eastern Ohio and Iowa; most abundant in New England and Middle 

 Atlantic States. 



alkalinity: mean 16.2 mg/1; range 2.5-57.5 mg/1 

 pH: mean 7.0; range 5.9-10.2 



7. Potamogeton diversifolius Raf. Fig. 8, Map 8 



Rare, known from only four locations in Massachusetts 

 and Connecticut. This species reaches the northeast extreme of 

 its range in New England. These New England populations occur 

 in acid waters as compared to the more alkaline waters further 

 west. Range extends from Massachusetts west to Pennsylvania, 

 northern Ohio, Illinois, Minnesota, Montana and Oregon, south to 

 Florida, Texas, California, and Mexico; most abundant in the 

 southeast. This species should be included on revised rare and 

 endangered plant lists of Massachusetts and Connecticut. 



alkalinity: mean 2.0 mg/1 

 pH: mean 6.6 



