SAGO PONDWEED 



Potamogeton pectinatus L. 



This pondweed has often been referred to as horsetail moss or 

 bushy pondweed when observed growing in irrigation canals. The most 

 widely accepted common name is "sago," meaning comblike, which 

 is descriptive of its vegetative growth character. The species is probably 

 the most widespread submersed aquatic weed found in irrigation canals 

 of the Western United States. It grows in a variety of habitats from 

 shallow, swift water to deep, still water and is often found in natural 

 lakes, reservoirs, and streams, which are the main sources of infestation 

 to irrigation systems. The vegetative form of sago pondweed is quite 

 variable and will differ under changes in environment. A large, 

 vigorous form of this species is often referred to as giant sago 

 pondweed. 



This plant produces a highly branched growth of slender stems and 

 leaves arranged in a rather fan-shaped order. The plant produces only 

 submersed leaves that are very narrow, linear, and somewhat triangular 

 in cross section. Leaf tips are often long, tapering to points (insert 1). 

 Flowers and the nutlike fruits are produced in an interrupted 

 arrangement on a long, slender, terminal stem that floats at or near 

 the water surface (insert 2). The plant is reproduced in subsequent 

 growing seasons primarily by the vegetative tubers and occasionally by 

 seed. Dissemination of tubers and fragmentation of vegetative plant 

 parts can spread the plant during growing periods. The fleshy tubers 

 (insert 3) are produced in considerable numbers at the ends of 

 underground stems, or rhizomes, growing at depths from 0.1 to 1 

 meter or more in canal soil. Occasionally, tubers are produced above 

 the soil surface in the axils of stem branches. Because of the extensive 

 rhizome runner and tuber development of this species, a single plant 

 spreads over a considerable area. 



