AQUATIC PLANTS IN POND CULTURE. 17 
The water clover (Marsilea quadrifolia) is excellent for shade 
and shelter, is ornamental, and of early growth. It is objection- 
able 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 pro- 
ducer, harboring the small forms 
which are especially good as food 
for young fish, and as an oxy- 
genator it is found remarkable. 
It is fairly good for shelter and 
as an aquarium plant. 
The spatterdock (Vymphea 
advena) is valued chiefly as an 
ornament 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 pro- 
vide favorable breeding places for 
insect larve or other minute ani- 
mal life. Itis found in 1 to4 feet Fic. 18.—Water clover (Marsilea quadri- 
of water. 
The long-leaved pondweed (Po- 
Fic. 19.—Large yellow pond-lily (Nymphea 
advena). Found in ponds and slow streams, 
New Brunswick and Nova Scotia to Rocky 
Mountains, south to Florida, Texas, and 
Utah. (After Britton & Brown.) 
Callea also spatterdock. 
folia). Found along the shores of Bantam 
Lake, Litchfield County, Conn., whence it 
has been introduced into various parts of 
the country, notably eastern Massachu- 
setts. Native cf Europe and Asia. (After 
Britton & Brown.) 
Fic. 20.—Long-leaved pondweed (Po- 
tamogeton lonchites). Found in ponds 
and slow streams, New Brunswick to 
Washington, south to Florida and Cali- 
fornia. (After Britton & Brown.) 
tamogeton lonchites) does not rank with the two other Potamogetons 
mentioned here, being but fairly good in any of the important respects. 
