1. Alisma gramineum Lej. Fig. 1, Map 1 



Locally abundant in calcareous waters and shores of Lake Cham- 

 plain and its tributaries. Plants are often found submersed in water to 

 a depth of about one meter. This variable species is sometimes divided 

 into two or three dubious varieties based primarily on vegetative fea- 

 tures which appear to be environmentally induced. First discovered in 

 New England in 1961 at Shelburne Bay on Lake Champlain (Coun- 

 tryman, 1968), this species appears to be spreading rapidly throughout 

 the lake region. Range extends from Vermont and southwest Quebec 

 west to Wisconsin, Alberta, and British Columbia, south to South 

 Dakota, Colorado, Nevada, and northern California. 



alkalinity: 47.5 mg/1 

 pH: 7.5 



2. Alisma plantago-aquatica L. 



2a. A. plantago-aquatica var. americanum Schultes and Schultes 

 Fig. 2, Map 2 



Scattered throughout New England along shores, in marshes, 

 ponds, streams, ditches, and in shallow water. This northern taxon is 

 treated by some authors as Alisma triviale Pursh. Range extends from 

 Quebec west to British Columbia, south to Maryland and west Vir- 

 ginia, Michigan, Iowa, Nebraska, New Mexico, Arizona, California, 

 and northern Mexico. 



alkalinity: mean 30.5 mg/1; range 13.5-47.5 mg/1 

 pH: mean 7.0; range 6.5-7.5 



2b. A. plantago-aquatica var. parviflorum (Pursh) Torrey Fig. 2, 

 Map 3 



Abundant along shores, in marshes, ponds, streams, ditches and 

 in shallow water throughout New England. This more southern taxon 

 is treated by some authors as Alisma subcordatum Raf. Most plants of 

 var. americanum and var. parviflorum are distinct at the extremes of 

 their geographical ranges but in New England intermediate plants 

 occur, sometimes making identification difficult. Range extends from 

 Maine west to New York, Ontario, Minnesota, and Nebraska, south to 

 Florida, and Texas. 



alkalinity: mean 69.5 mg/1; range 11.0-290.0 mg/1 

 pH: mean 7.3; range 6.5-8.4 



