AQUATIC PLANTS IN POND CULTURE. 



19 



included semiaquatic or border plants, but arrowhead {Sagittaria 

 Jongirostra) and water plantain {Alisinaplantago-aqKatica) are given 

 an important place among the plants at this station. A more care- 

 ful investigation may lead to the conclusion that certain semiaquatic 

 plants are equal in value to some of their exuberant companions of 

 the deeper water. 



The curled-leaved pondweed {Potamogeton crispus, fig. 5) is consid- 

 ered the most desirable plant at this station. Its roots are on muck bot- 

 tom in water up to G feet deep, and it throws up a slender stalk about 

 2 inches above the surface, on the tip of which is a small white blossom. 

 The plant grows luxuriantly both in summer and winter, and flour- 

 ishes in both cold and warm 

 water j^onds. It furnishes 

 abundant shade and protec- 

 tion, and is a good breeding 

 place for aquatic insects. It 

 is also easy to control, and 

 can be removed from the 

 ponds without injury to the 

 fish. Its only objectionable 

 character is that where the 

 soil is fertile it grows more 

 luxuriantly than is desirable. 



The water weed {Philotria 

 canadensis, fig. 9) exhibits 

 the same characters here as at 

 the Fish Lakes station, but 

 is more highly esteemed, 

 being given second place. 



The parrot-feather {Myr- 

 ioj)hyllum jjroserpinacoides, 

 fig. 2), rooting in muck bot- 

 tom in water up to 6 feet 

 deep, reaches to the surface 



and throws up a slender stalk about 2 inches above, with a small white 

 blossom at the tip. Because of its value as a shade for fish and as 

 a breeding j)lace for aquatic life, this plant is ranked third in im- 

 portance at this station. It is also an excellent plant for aquaria. 



The arrowhead {Sagittaria longirostra) is but semiaquatic, but is 

 a valuable shade and shelter for the young fish. It can also be re- 

 moved easily and is not difficult to control. It usually roots in soft 

 clay up to 2 feet, and throws up a slender stalk with white blossoms 

 above the surface. The leaves are killed by the first frost, and the 

 plant branches out from the rootstocks in the spring. 



Fig. 23. — Long - beaked arrowhead {Sai/ittarin 

 lotigirostra). Found in swamps and along 

 ponds, New Jersey and Pennsylvania to Ala- 

 bama. (After Britton & Brown.) 



