EURASIAN WATERMILFOIL 



MyriophylluTn spicatum L. 



Eurasian watermilfoil, like the northern watermilfoil 

 {Myriophyllum exalbascens), is completely submerged except for the 

 flowering spikes. The stems are branched slightly and can vary in color 

 from a pale greenish-yellow to a full pink. The leaves are separated into 

 12 to 24 pairs of filamentlike divisions (insert 1) and develop on the 

 stem, usually four in a whorl. Northern watermilfoil's leaves are similar 

 but usually have 14 or less pairs of divisions. The flowers are small and 

 are usually in whorls of four along a slender terminal spike which 

 extends above the water surface. All but the lower two to four whorls 

 of floral bracts (leaves beneath and enclosing the flowers) have smooth 

 edges and are shorter than the flowers and fruits. The lower floral 

 bracts have comblike or serrated edges and are longer than the fruits 

 (insert 2). The lower bracts of the northern watermilfoil are serrated, 

 but are usually shorter than the fruits in length. The nuflike fruits of 

 the eurasian variety have exhibited long periods of dormancy and 

 erratic germination. Winter buds, apparently, are not produced. 



Eurasian watermilfoil has become a nuisance in lakes, streams, and 

 irrigation systems in recent years. It colonizes new sites mainly by 

 vegetative fragments which develop roots, sink, and establish new 

 plants. This fragmentation is responsible for the rapid spread of this 

 weed and the difficulty in controlling it. 



28 



