10 



AQUATIC PLANTS IN POND CULTURE. 



species. It makes an ideal groAvth and affords abundant cover for 



the fish and for the minute life upon which the fish feed, and is appar- 

 ently a good oxygenator. At the same 

 time it offers but little obstruction to 

 seining operations, owing to its slender 

 feathery growth. Even for ponds hav- 

 ing rich muck bottom it has been found 

 most satisfactory, though here consid- 

 erable work is required to remove it 

 when preparing for seining. 



For ponds with sterile bottoms of 

 clay, sand, or gravel, where fox-tail 

 will not thrive, parrot-feather {Myri- 

 ophyUwrn froBerpinacoides) attains an 

 excellent growth and affords abundant 

 lodgment for minute aquatic life and 

 for the alevins ; it also provides a suffi- 

 cient amount of shade for the brood fish 

 and suitable cover for their nesting 

 places. Large-mouth black bass seem 

 to prefer the fibrous roots of these 



plants to all other nesting materials. Both plants disappear from 



the warmest parts of the ponds by midsummer and are replanted in 



the fall or following spring. Near 



the inflow, especially of ponds which 



are abundantly supplied with water, 



the plants thrive throughout the year. 



The parrot-feather is more suscepti- 

 ble to high temperatures than the 



fox-tail. These two plants have 



proved so satisfactory at Cold 



Springs that the superintendent lias 



seen little occasion to experiment 



with other species. 



FISH LAKES, WASHINGTON, D. C. 



Fig. 1. — Spiked water-milfoil {My- 

 riophyUum sincatum). Found in 

 deep water, Newfoundland to 

 Manitoba and the Northwest Ter- 

 ritory, south to Florida, Iowa, 

 Utah, and California. (After 

 Britton & Brown.) 



Commonly known as fox-tail. 



Although the Fish Lakes at Wash- 

 ington are no longer maintained, 

 observations upon the characteristics 

 of the plant life are valuable for 

 purposes of comparison. The bot- 

 toms of the ponds were of dark fer- 

 tile soil, the maximum water temperature was about 87° F., and 

 the plant growth was extremely dense. Whether the elimination 



Fii!. 2. — Chilean water-milfoil {My- 

 riophylhim proserpinacoides) . (After 

 Britton & Brown. ) Native of Chile, 

 introduced in various localities in 

 the United ^States, where it is 

 known chiefly as " parrot-feather." 



