18 



Key to Species 



1. Fronds long-stalked, 6-15 mm long; lateral fronds usually remain 

 attached to parent frond (fig. 6A,B); usually suspended below the 

 surface, often in tangled mats. 



1. L. trisulca 



1. Fronds sessile or nearly so, less than 6 mm long; forming single 

 plants or small rosettes (fig. 6C,D,E); floating on surface. 

 2. Fronds elliptic to linear-oblong, less than 0.5-1.5 mm wide with 

 sides somewhat parallel and ends rounded (fig. 6C), obscurely 

 1-nerved. 



2. L. valdiviana 



2. Fronds broadly oblong, obovate or suborbicular, 1.2-3.0 mm broad 

 with all sides curved (fig. 6D,E), obscurely 3-nerved. 

 3. Root sheath with lateral wings; root-tip pointed, frond with 

 apical and central papilla prominent. 



L. perpusilla 



3. Root sheath without lateral wings; root-tip rounded, frond with 

 apical papilla not prominent. 

 L. minor 



1. Lemna trisulca L. Fig. 6, Map 11 



Common in quiet alkaline waters of western New England, 

 uncommon in less alkaline waters of eastern New England. This 

 species occasionally forms extensive tangled mats encrusted with 

 marl or may be tangled with other submerged aquatics. Range extends 

 from the Magdalen Islands, Quebec and Nova Scotia west to Alaska, 

 south to Florida, Alabama, Arkansas, Texas, New Mexico, and 

 California; nearly worldwide. 



Rare and endangered plant list: New Hampshire 



alkalinity: mean 60.4 mg/1; range 26.0-153.0 mg/1; (6) 

 pH: mean 7.3; range 7.0-7.4; (6) 



2. Lemna valdiviana Phil. Fig. 6, Map 12 



Uncommon in quiet waters, mainly in southern New England. 

 Range extends from northern New Hampshire and New York west to 

 Ohio, southern Michigan, Illinois, Wyoming, and Oregon, south 

 throughout the United States; Mexico and South America. 



Rare and endangered plant list: New Hampshire 



