(5) They make it more difficult to clear a pond of fish and also make proper 

 supervision more difficult. A dying off of fish, for instance, may not be 

 discovered and predaceous fish find hiding places and nesting places in the 

 labyrinth of reeds. 



Only a few welcome advantages of a svirface flora can be quoted as against these many 

 disadvantages, to wit: In cases of very sparse growth with oaaly a few stalks arising out 

 of the water, they will somewhat increase the chances for the development of aquatic life. 

 It is also true that a not too dense border of reeds, along the baxiks of wind-exposed ponds 

 gives the best protection against slides. 



TTith regard to their noxious character, the various species of a surface flora are to 

 be differentiated. 



Most harmful of all is the "Bottcherschllf (Typha latifolia and T. angustifolia) and 

 the "Ditch Reed" (Phragenites communis). 



Sonevrtiat less "hard", i.e. of less cellulose ccmtents are the "Sussgrasser" (sweet 

 grasses), i.e. the Glyceria species, sedge and reed bent-grass (Carex species), also 

 horsetail (Equisetum), bulrushes (Scirpus lacustris), flowering rush (Butomus umbellatus), 

 calmus (Acorus calamus), arrowhead (Saggitaria saggitifolia), water plantain (Alisma 

 plantago). For this reason they are not so harmful as the Typha and Phragnites species. 



Floating plants 



By this term I understand those plants which float upon the surface of the water and 

 are rooted in the water, not in the bottom of the pond. They will be found in profusion 

 only in wind-protected ponds (small tree-lined ponds in paiics, etc.), rich in foodstuffs. 



From the viewpoint of biological productivity, their presence is harmful since they 

 shade a pond almost completely without offering any compensating advantages. The liemna 

 and Azolla species belong in this class, also the less frequent Hydro charis . Winter buds 

 of these plants will sink to the bottom — as in the case of so many submerged plants — and 

 thereby will outlast even a winter drainage of the pond. 



Submerged plants 



Under this classification come all these larger plants (weeds, in the language of the 

 fishbreeder) which grow chiefly under the water level, even if their flowers and floaters 

 reach up to tiie surface of the water. And although bacteria-plankton, "coating" and 

 "sessile" plants should come under this heading, they are practically not counted among 

 them, since they form a group apart, on account of their specific adaptations. 



This flora plays a rather helpful role, i.e. in at least 50 per cent of the cases, 

 and for the following reasons: 



(1) They are the natural food of many aquatics. 



(2) They are the most iiiiportant factor for the development of Aquatics. 



(3) They are the ideal haunts for the vegetati-" fauna. 



(4) The softer species of these plants contribute to the foimation of productive 

 organic slime. 



(5) The decayed plants are a first class fertilizer in the follcfwlng year. 



(6) The submerged flora largely supplies the necessary oxygen, which so often 

 is of great inqwrtance in trout pond, winter pond, etc. The oxygen 

 production of the surface flora is far below the amount produced by^ 

 submerged plants. 



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