- 31 - 



this species follows Haynes (1974) who does not recognize 

 inf raspecif ic taxa due to the range of variability observed both 

 between and within populations. Hybrids between this species 

 and P. zoster if ormis may be called P_^ X long il igulatus Fernald 

 (Hayries and Williams, 1975). Range extends from eastern Quebec 

 to the Northwest Territories, south to northwest Connecticut, 

 New York, Indiana, Minnesota, Nebraska, Wyoming and northern 

 Utah; most abundant in the Great Lakes region. 



Rare and endangered plant lists: Massachusetts, Connecticut 



alkalinity: mean 76.1 rag/1; range 55.0-109.0 mg/1 

 pH: mean 7.5; range 7.0-8.4 



alkalinity: mean 49.1 mg/1; range 

 pH : mean 7.4; range 6.7-8.2 



16. Potamogeton pusillus L. var . pusillus Fig. 18, Map 18 



Uncommon in northeastern Maine, abundant in western New 

 England in alkaline waters. Includes both var. pusillus and 

 var. minor of Fernald (1950). Range extends throughout North 

 America from Newfoundland and Labrador west to Northwest 

 Territories and Alaska, south to Mexico and Guatemala. 



alkalinity: mean 64,1 mg/1; range 25.0-114.5 mg/1 

 pH : mean 8.1; range 7.3-10.2 



17. Potamogeton pusillus L. var. tenuissimus Mert. and Koch 

 Fig. 19, Map 19 



Extremely common in acid and alkaline waters throughout 

 New England; occasionally in brackish water along the coast. 

 Includes all varieties of P^ berchtoldii Fieber (Haynes, 1974) 

 as treated by Fernald (1950) . Range extends from Newfoundland 

 to Alaska, south to northern Florida, Louisiana, and California; 

 most abundant in the northeast. 



alkalinity: mean 32.4 mg/1; range 2.5-179.0 mg/1 

 pH : mean 7.1; range 5.6-10.2 



18. Potamogeton pusillus L. var. gemmipar us Robbins Fig. 20, 

 Map 20 



Uncommon in acid waters of eastern New England. Treated 

 by Fernald (1932) as P_^ geramiparus (Robbins) Morong; however, 

 Haynes (1974) recognized it as a variety of P_^ pusillus . This 



