LEAFY PONDWEED 



Potamogeton foliosus Raf . 



This plant develops a dense mat of slender, horizontal stems or 

 rhizomes near the aquatic soil surface, rooting at each stem-joint or 

 node. The erect stems develop to varying lengths depending upon the 

 depth of water in irrigation canals. This species derives its common 

 name "leafy" from the extensive foliage it produces. This pondweed 

 is commonly found in canals and drains as an early season invader and 

 sometimes in late season, but is not as prevalent during the 

 midsummer. This is probably due to its inability to successfully 

 compete with the more vigorous pondweed species, such as American 

 and sago pondweeds where they coexist, and its early age of maturity. 



Leafy pondweed is completely submersed in habit, producing loose 

 branches that present a bushy appearance with stems that seldom 

 reach the surface in deep water. The leaf blades are narrow and flat 

 and have a definite midrib vein that is white or yellowish in color. 

 Flowers and fruiting spikes are produced on short stems arising from 

 the terminals of the stems. 



The plant overwinters by producing a tight, compact vegetative 

 bud in the axils of the branches that is rather hard when mature 

 (insert 1 ). These winter or axillary buds are produced in considerable 

 quantities as the plant progresses to vegetative maturity (insert 2) and 

 sink to the bottom when the plant disintegrates. 



Leafy pondweed is widespread throughout the Western United 

 States and is among the first pondweed species to invade an irrigation 

 canal. It becomes overshadowed by more persistent deep-rooted 

 pondweeds as the system ages, although it will continue to grow in 

 association with these other species. It develops and matures rapidly 

 during the warm summer months. Consequently, it is often found in 

 intermittently watered canals and drains. As the plant reaches 

 maturity, the stems fragment readily, producing considerable floating 

 vegetation. 



