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in rasch fliessendem Wasser entstandene Form von P. natans an- 

 sehen . . . P. fluitans is nur mit unausgebildeten Früchten bekannt; 

 manche hierher gerechneten Pflanzen sind wohl als P. lucens x 

 natans anzusehen, so namentlich auch die var. stagnatilis Koch." 



From this appears that according to the view of Buchenau 

 P. fluitans includes two different plants of which the one is a form 

 of P. natans and to him the real P. fluitans Roth, while the other 

 is the bastard P. lucens x natans to which Buchenau, like others, 

 reckons P. fluitans var. stagnatilis Koch. 



Another view is given by the English Potamogeton students 

 Fryer and Bennet who mean that P. fluitans comprehends in 

 the first place an independent species; and, secondly, a plant that 

 is supposed to be a bastard, namely P. lucens x natans. This 

 view is founded upon the fact, that P. fluitans in some localities 

 is abundantly fruiting like other species of Potamogeton, while on 

 many other localities it never appears with w T holly developed fruit 

 but is always barren. Though the opinion that P. fluitans includes 

 two different plants is fully right, what later on I am going to 

 prove, it has not at all been accepted everywhere; this, however, 

 is not difficult to understand, because hitherto a sufficient proof 

 has not been given. The distinction between the two forms was 

 only founded on the want of or the presence 'of- wholly developed 

 fruit. This, however, is not only a very unpractical distinction but 

 even not at all conclusive, as we know many species of plants 

 which can appear in a fully sterile form that will only multiply 

 vegetatively. Therefore, as the case is at present, Ascher son and 

 Gr aebner 1 ) were right when saying: „Wir können uns dieser 

 Anschauung nicht anschliessen, denn bei der grossen Variabilität 

 dieser Formen scheint es sehr gewagt, hier eine künstliche Trennung 

 auf höchst veränderliche Merkmale hin vorzunehmen." 



Ascherson and Graebner, contrasting with Fryer and Bennet, 

 comprise all P. fluitans-îovms to one species supposing it to be of 

 hybrid origin and the fruiting individuals to be explained in the 

 way, that the bastard under certain conditions in the course of 

 time should have developed to be fruiting. Hence there is good 

 reason for once more to take up the question for a renewed 

 examination. 



J ) Ascherson, P. und Graebner, P., Synopsis der mitteleuropäischen 

 Flora. I. Bd. 



