14 



U. S. BUREAU OF FISHERIES. 



and as a breeding place for aquatic life this plant is ranked third in 

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

 The arrowhead {Sagittaj^a longirostra) is but semiaquatic, but 

 forms a valuable shade and shelter for the young fish. It can also 

 be removed 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 blos- 

 soms above the surface. The leaves are killed by the fii-st frost, and 

 the plant branches out from the rootstocks in the spring. 



The water plantain {AUsma plantago-aquatica) is another border 

 plant, being found about the edges of ponds in water only 4 to 6 



inches deep, its leaves floating on the sur- 

 face. It is valuable for the same charac- 

 ters exhibited b}^ the arrowhead. 



The Chara at this station is a large form 

 •\V^M\U with long, slender internodes, growing in 



\v\luU/7 ^Y\ ponds, whether they are fed by spring 



or creek water. It is an excellent food 

 producer, but grows so densely that the 

 fish can with difficulty get through it, and 

 it is so heavy that it will not float w^hen 

 cut loose from the bottom. \Alien a jDond 

 is drawn, it settles down like a blanket, 



Fig. 25. — Chnrm fra^ilis. 

 A common form of 

 Chara. (After Stras- 

 burger, Noll, Schenck, 

 & Schimper.) 



Fig. 26. — Sweet-scented white water 

 lily {Castnlia odorata). Found in 

 ponds and slow streams. Nova Scotia 

 to INLanitoba, south to Florida and 

 Louisiana. (After Britten & Brown.) 



entangling the young fish so that it must be picked over by hand in 

 order to extricate them. Its objectionable characters, in fact, are 

 so great that it is only by comparison and on negative grounds that 

 its merits are admitted by the superintendent. 



A number of years ago the ponds at Wytheville were well stocked 

 with curled-leaved pondweed, waterweed, and limeweed, with a few 

 water lilies (Castalia odorata) scattered here and there; but water 

 lilies increased from year to year until they took complete posses- 

 sion of several of the ponds. They became so dense as entirely to 

 exclude the light from the ponds, and in consequence all the sub- 



