1 . Leaves ovate to obovate in outline, 4-9 cm wide, sinus typically open 

 with widely divergent lobes (fig. 4); flowers 3.3-8 cm broad, petals 

 8-17. 

 3. N. tetragona 



1. Nymphaea odorata Ait. Fig. 3, Map 3 



Extremely common throughout New England in sluggish 

 streams, ponds, and lakes. Light pink-flowered individuals are fre- 

 quently encountered and are treated by some authors as forma rubra 

 Guillon. Occasionally plants with dark pink to light red flowers are 

 found which are likely to be the European Nymphaea alba L. forma 

 rosea Hartm., differentiated from N. odorata by having 20-24 petals 

 which are rounded at the tips. Nymphaea odorata has 17-32 petals 

 which gradually taper to subacute tips. Range extends from New- 

 foundland and southwestern Quebec west to Ontario, Minnesota, and 

 Manitoba, south to Florida, Iowa, Nebraska, Kansas, Oklahoma, 

 Texas, and Arizona. 



alkalinity: mean 25.0 mg/1; range 2.0-141.5 mg/1; (121) 



pH: mean 7.0; range 5.3-9.5; (117) 



2. Nymphaea tuberosa Paine Fig. 3, Map 4 



Common in alkaline waters of the Lake Champlain Valley of 

 Vermont, uncommon elsewhere in New England, but sometimes 

 planted as an ornamental. Floating leaves are often very large (up to 

 40 cm wide) and plants along the shoreline may have leaves elevated 

 above the surface. Two characters often utilized to distinguish 

 N. odorata and N. tuberosa are time of day flowers are open and the 

 degree of flower odor. Neither of these traits are reliable. Population 

 and transplant studies by Williams (1970) suggested that characters 

 distinguishing N. tuberosa from N. odorata may not be constant. In 

 calcareous waters of the Lake Champlain Valley the two taxa are 

 easily distinguished. Likewise, introduced plants of N. tuberosa in 

 acidic waters of eastern New England retain their distinctive features. 

 Hence, we presently continue to recognize them as two species. Range 

 extends from southwestern Quebec west to northern Ontario, Minne- 

 sota, and Nebraska, south to Maryland,^ Ohio, Indiana, Illinois, 

 Arkansas, and northeastern Oklahoma. 

 Rare and endangered plant lists: Massachusetts, Connecticut 



alkalinity: mean 59.0 mg/1; range 10.0-153.0 mg/1; (21) 



pH: mean 7.6; range 6.8-8.6 (21) 



3. Nymphaea tetragona Georgi Fig. 4, Map 5 



Rare, in quiet streams and protected waters of moderate alkalin- 

 ity of northern and northwestern Maine. The North American taxon 



