1918-19.] BOTANICAL SOCIETY OF EDINBURGH 315 



Notes on Dr. Hagstrom's "Critical Researches on 

 PoTAMOGETON, 1916." By Arthur Bennett, A.L.S. 



(Read 4th December 1918.) 



Dr. Hagstrom's material was mainly restricted to the 

 Scandinavian herbaria, with a few from St. Petersburg 

 and Berlin ; hence the distribution of the extra-European 

 species is very meagre. To obviate this I sent him full 

 particulars of all the species he has treated of, relating 

 to their distribution. Still, it shows their herbaria are 

 rich ill the crenus. It is to be regretted he could not 

 consult our herbaria, nor those in Paris, Munich, and 

 Vienna, nor Boi.ssier's and De Candolle's, though he had 

 ray papers on those herbaria. In this work the author 

 has contributed a large amount of original work. He 

 relies greatly on anatomical characters — too much, it seems, 

 when one tries to verify his facts b}^ the aid of specimens 

 grown for years. My late friend, Mr, Fryer, for many 

 years tested the plants by growing them in tubs and in 

 a pond in his garden, and his work shows that too much 

 reliance cannot be placed on Dr. Hagstrom's conclusions ; 

 in fact, as in all systematic botany, all and every aid is 

 needed that can be brought to bear before we can safely 

 say, " This is that, and that is this." 



The following notes are a running commentary on his 

 work, taking it in the sequence he adopts. 



Potamogeton Jiliformis, Pers. — As to Fries' note on 

 Boccone's tig., Ic. descrip. Sic. et Mel. Gall. It., t. 20, f. 5, 

 1674, named " pusillunn Jluitans," if it is not a fair one 

 of Wolfgang's P. fascicidatus, what is it ? Not jpusillus, 

 for certain. He quotes under filiformis, P. maritiinuin, 

 Pohl; but Pohl places this as a synonym under his loectinatus, 

 adding P. inarinus, L., with a reference to Eng. Bot., t. 823, 

 and Fl. Danica, t. 186, both of which are pectinahis, Linn. ; 

 so I do not see how it can be placed as a synonym of Jili- 

 formis, as it is by the author, I quite agree with the author 

 in making /i^i/o?'»i is a full species, equal to jjectinatus. 



P. vaginatus, Turcz, (Europe, Asia, America). — I cannot 

 help thinking there is some error as to this species. The 



