18 BULLETIN" 465, U. S. DEPARTMENT OF AGRICULTURE. 



A pondweed with abundant tuberous rootstocks (P. heterophyllus, 

 fig. 11) promises to be of exceptional value, since it changes its form 

 and continues growth when the water surrounding it lowers or dries 

 up. Parts of this plant for propagation are not yet on the market. 



DISTRIBUTION. 



The range of the sago pondweed is from coast to coast as far south 

 as Florida, Texas, the Mexican plateau, and Lower California, north 

 to Nova Scotia and Hudson Bay, and along the Pacific coast up to 

 latitude 62° north (fig. 19). The distribution of other species has 

 been indicated above. 



Fig. 18. — Tubers of sago pondweod. (Natural size.) B4M 



PROPAGATION. 



Sago pondweed is easily transplanted by means of the seeds, which 

 are usually gathered with a short section of the top of the plant. 

 Growth from seed may be so delicate as to escape notice the first 

 season, and yet the pond may be filled the second season, for the plant 

 grows much more luxuriantly after the root system becomes well 

 established. Quicker results may be obtained by planting tubers, but 

 these are rather difficult to obtain in quantity. Success has recently 

 been achieved in transplanting young plants of this species, even 

 after shipping them considerable distances. 



Stations of the U. S. Bureau of Fisheries use pondweeds to some 

 extent in fish ponds and no difficulty seems to be encountered in 



