10 



U. S. BUREAU OF FISHEEIES. 



The fennel-leaved pondweed {Pota7nogeton pectinatus) is some- 

 \A'hat objectionable on account of its excessive growth. It is, 

 however, a good food producer and a fair oxygenator and is fairly 

 good for shelter. It is found in 1 to 4 feet of water. 



The pickerel weed {Pontederia cordata)^ found in 6 to 12 feet of 

 water, is not especially valuable in fish culture, althougli it has some 

 merit for ornamental qualities, for shade, and for shelter. It is not 

 < liought to be a good oxygenator or food producer. 



The two duckweeds {Spirodela polyrhiza and the more common 

 Lemna niinor) are no* highly esteemed, though not especially ob- 

 jectionable. The larger form is quite ornamental, and both are of 

 early growth. For fish-cultural purposes, however, their poor 

 qualities as food producers and oxygenators make them insignificant. 



The water clover {Alardlea quadrifolia) is excellent for shade and 

 shelter and is ornamental and of early growth. It is objectionable 



Fig. 13. — Water lily, or floating heart 

 (Umiumthenhu m niimpluBoides ) . Nat- 

 uralized in ponds, District of Colum- 

 bia. Native of Europe and Asia. 

 (After Britton & Brown.) 



Fig. 14. — Fennel-leaved pondweed (Pota- 

 m-ogeton peetinattifi). Found in fresh, 

 braclsish, or salt water, Cape Breton 

 to British Columbia, south to Florida, 

 Texas, and Califoraia. Also in Eu- 

 rope. (After Britton & Brown.) 



in shallow ponds, however, completely covering the surface to a 

 depth of about 2 feet. 



At this station the limeweed (Chara) is valued as a food producer, 

 harboring the small forms that are especially good as food for 

 3'oung fish, and as an oxygenator it is found remarkable. It is fairly 

 good for shelter and as an aquarium plant. 



The spatterclock {Nymphcea advena) is valued chiefly as an or- 

 nament and for the shade and shelter it affords. It is also of early 

 growth, but it is a poor food producer on account of its long, smooth 

 stems, which do not provide favorable breeding places for insect 

 larva3 or other minute animal life. It is found in 1 to 4 feet of 

 water. 



The long-leaved pondweed {Potamogeton lonchites) does not rank 

 with the two other Potamogetons mentioned here, being but fairly 

 good in any of the important respects. 



