AQUATIC PLANTS IN POND CULTURE. 9 



the objectionable characters of the undesirable. It is hoped thus 

 to aid in determining the relative value of each, or at least to afford 

 data which will be useful in future work, at the same time empha- 

 sizing the fact that present knowledge of the subject is all too limited. 

 These notes are not based upon biological or other scientific investi- 

 gation, but are gained from the observations and experience of prac- 

 tical fish culturists. They are moreover presented as pertaining only 

 to the particular field of pond culture conducted by the Bureau. 

 Their application beyond this is yet to be determined. 



It may be assumed that all aquatic plants harbor a certain amount 

 of minute animal life. In the following descriptions, therefore, the 

 term " food producer " is applied to plants conspicuous for the large 

 quantity of small animal forms living or breeding thereon. The 

 term " oxygenator " is applied to plants believed to be especially use- 

 ful in keeping water in a proper condition by throwing off oxygen. 

 The w^ord '" shelter " is applied to plants which afford the small fish 

 a hiding place and protection from the large ones. The term " orna- 

 mental " is used to designate those plants which extend above the 

 surface and beautify the ponds. The depth of water in which the 

 plants are found as here mentioned applies to the ponds of the 

 respective stations in question. It is recognized that some of the 

 plants thrive in much deeper ponds and lakes. 



Common names of the plants are given, but as these are often of 

 restricted local application, the botanical nomenclature also is used, 

 and for more ready identification figures have been inserted for 

 almost every species. All but one of the cuts are copied from Britton 

 and Brown's " Illustrated Flora of North America." The figure of 

 Chara is taken from the " Text Book of Botany " by Strasburger, 

 Noll, Schenk, and Schimper. The geographical range of the respec- 

 tive species likewise is taken from these authorities. 



For the identification of a large number of these plants the bureau 

 is indebted to Messrs. J. N. Rose and G. H. Shull, of the United 

 States National Herbarium, Smithsonian Institution, and also to 

 the Division of Botany, Department of Agriculture. 



COLD SPRINGS, GA. 



At this station the water supply is from a large spring and the 

 maximum water temperature is about 82° F. The water contains 

 only a trace of lime, and as a result some difficulty has been ex- 

 perienced in stocking the p)onds with aquatic plants, but efforts in 

 this direction have resulted as follows, as reported by the suiDcrin- 

 tendent, Mr. J. J. Stranahan: 



For ponds with fairly fertile bottoms with an admixture of muck 

 and clay, the fox-tail {Myriophyllum spicatum) excels all other 

 63994—09 2 



