FLOATING AQUATIC 

 WEEDS 



A number of floating plant pests are known to exist on Western 

 irrigation systems. Some of these plants can survive either completely 

 free-floating or they may root in the bottom mud when growing in 

 shallow waters. Certain species are almost amphibious and will extend 

 onto mudbanks. Fortunately for Western irrigation systems, a few of 

 the very aggressive species will not survive freezing temperatures and 

 occur only in isolated areas in the Western United States. Two of these 

 are waterhyacinth and alligatorweed. These species are illustrated to 

 acquaint the irrigation operator on more southerly projects with them 

 in the event these plants should extend their range. 



Duckweed, a very cosmopolitan floating aquatic weed, is included 

 to illustrate a typical plant of this group. A number of plants 

 representing many plant families are true-floating aquatics and do 

 occur on Western irrigation systems, but were not included because 

 of the very limited problems they produce. Some of these species found 

 in isolated areas in the West are waterlettuce, watervelvet, 

 waterprimrose and waterfern. The reader is referred to publications 

 cited in the bibliography for aid in their identification in the event 

 they might be encountered. 



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