AQUATIC PLANTS IN POND CULTURE. 15 
The needle spikerush (Zleocharis acicularis) is of very little 
value except for its 
early growth. The fine, 
smooth culms are very 
easily cleaned by the 
large-mouth black bass, 
which cast their spawn 
upon them. 
One of the water- 
lilies (Castalia tube- 
rosé), which furnishes 
shade and shelter, is or- 
namental and of value 
because of its early 
growth. It serves as 
a good protection to 
young fish from pre- 
daceous birds. 
Floating heart (Lim- 
nanthemum nymphe- 
oides), while but fairly 
good as a food pro- 
Fie. 12.—Tuberous white water-lily (Castalia tube- 
Lake Champlain west through Great Lakes 
to Michigan, south to Trenton, N. J., Meadeville, Pa., 
and eastern Nebraska. (After Britton & Brown.) 
ducer, is excellent for shade, shelter, and ornament and is fairly 
Fie. 13.—Water-lily, or floating heart (Limnan- 
themum nympheoides). Naturalized in ponds, 
District of Columbia. Native of Europe and 
Asia. (After Britton & Brown.) 
hardy. 
The fennel-leaved pond- 
weed (Potamogeton pecti- 
natus) 1s somewhat objec- 
tionable on account of its 
excessive growth. It is, 
however, a good food pro- 
ducer, a fair oxygena- 
tor, and fairly good for 
shelter. Found in 1 to 4 
feet of water. 
The pickerelweed (Pon- 
tederia cordata), found in 
6 to 12 feet of water, is 
not especially valuable in 
fish culture, although it 
has some merit for orna- 
mental qualities, for shade, 
and for shelter. It is not 
thought to be a good oxy- 
genator or food producer. 
