AQUATIC PLANTS IN POND CULTURE. 19 
included semiaquatic or border plants, but arrowhead (Sagittaria 
longirostra) and water plantain (Alisma plantago-aquatica) 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 6 feet deep, and it throws up a slender stalk about 
2 inches above the surface, on the tip of which isa small white blossom. 
The plant grows luxuriantly both in summer and winter, and flour- 
ishes in both cold and warm 
water ponds. 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 waterweed (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 (J/yr- 
iophyllum proserpinacordes, Fic. 23.—Long-beaked arrowhead (Sagittaria 
fig. 2), rooting in muck bot- longirostra). Found in swamps and along 
: ponds, New Jersey and Pennsylvania to Ala- 
tom in water up to 6 feet bama. (After Britton & Brown.) 
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 place 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. 
