14 



2. Upper surface raised to a conspicuous papule (fig. 5C). 



3. W. brasiliensis 



Wolffia Columbiana Karsten Fig. 5, Map 6 



Widely scattered in alkaline waters, rarely in acidic waters; 

 ditches, ponds, lakes, and slow-moving rivers in New England. This 

 and other species of Wolffia are often associated with stagnant and/or 

 polluted waters. Wolffia is probably more common in New England 

 than documented. Presently it is spreading northward, probably with 

 the help of man. The plants readily stick to boats and are thus 

 dispersed from one body of water to another. Range extends from 

 southern Maine, central New Hampshire, and southwestern Quebec 

 west to southern Ontario, Michigan, Wisconsin, Minnesota, and 

 Manitoba, south to Florida, Louisiana, and eastern Texas; California 

 south to northern South America. 



Rare and endangered plant list: Maine 



alkalinity: mean 48.0 mg/1; range 12.0-107.0 mg/1; (10) 

 pH: mean 7.4; range 6.8-7.9; (10) 



2. Wolffia borealis (Engelm.) Landolt Fig. 5, Map 7 



Rare in quiet waters of ditches, ponds, lakes, and slow-moving 

 rivers in New England. This species appears in most manuals as 

 W. punctata Griseb. but the name W. borealis has recently been 

 applied by Landolt (1980). Range extends from New Hampshire, 

 Vermont, Massachusetts, and Connecticut west to New York, Ontario, 

 southern Minnesota, south to Florida, and eastern Texas; Washington 

 and Oregon; West Indies. Most abundant in the central and eastern 

 states. 



Rare and endangered plant list: Vermont 



alkalinity: mean 34.4 mg/1; range 12.0-107.0 mg/1; (5) 

 pH: mean 7.3, range 6.8-7.9; (5) 



3. Wolffia brasiliensis Weddell Fig. 5, Map 8 



Rare in widely scattered locations in Massachusetts and Connec- 

 ticut. Landolt (1980) applies the name W. brasiliensis Weddell to the 

 taxon referred to as W. papulifera C. H. Thompson in most manuals. 

 Range extends from Massachusetts and Connecticut west to Illinois, 

 Missouri, and Kansas, south to Florida and Texas; Mexico. 



Rare and endangered plant list: Connecticut 



