154 The Scottish Naturalist. 



and I found it again in Fingask Loch, near Blairgowrie, on the 

 ioth of the present month. This is a valuable addition to the 

 flora of Perthshire. 



Potamogeton Zizii Mert. et Koch. 



This interesting but puzzling plant I have not seen described 

 in any manual of British botany. It was, I believe, first observed 

 as a British plant in Cauldshiel Loch near Melrose ; and Dr B. 

 White informs me that he has it in his herbarium from Cluny 

 Loch and the Loch of the Lowes. I gathered it this summer in 

 Rescobie, Cluny, and Ardblair Lochs — in the first-mentioned 

 on the 26th of July last. There seems to be some difference of 

 opinion amongst those who have distributed specimens as to the 

 place this Potamogeton should hold amongst its congeners. Most 

 of the German authors incline to consider it a variety of P. 

 heterophyllus Schreb. Garcke in his ' Flora von Deutschland ' — 

 the only work of the kind to which I have access — thus describes 

 it under P. gramineus L. : " Leaves very large, blunt, especially 

 the upper ones ; always mucronate, and often undulate." The 

 Scandinavian authors, on the other hand, I am told, place it 

 nearer to P. lucens. Its fruit is gibbous, like that of the former, 

 and the uppermost leaves are sometimes a little different from 

 the others, but in habit and general appearance it resembles the 

 latter much more closely. In my opinion it ought to rank as a 

 species between P. heterophyllus Schreb. and P. lucens L. Mr 

 Arthur Bennett of Croydon, in a letter to me on the subject, re- 

 marks that perhaps Chamisso's idea is nearest to nature, who 

 includes heterophyllus, lucens, and Zizii as sub-species under one 

 super-species, P.proteus Cham, et Schl. It is perhaps worthy of 

 remark that we found it more frequently barren than fertile. In 

 Rescobie, however, most of the specimens we observed were in 

 exceptionally good condition. 



Potamogeton decipiens Nolte. 

 This very rare Potamogeton was discovered in Rescobie Loch 

 by Messrs Graham, Knox, and Stewart, and myself, on the 26th 

 of July last. This is, I believe, the first time it has been ob- 

 served in Scotland. Like P. Zizii, it does not seem to fruit 

 very freely. In a rich bed of it we got only a very few spikes, 

 and no well-matured fruit. In close proximity we found a fine 

 bed of the delicate variety of P. nitens Web., the curvifolius of 

 Hartman. 



The Schoolhouse, Rattray, 31^ August 18S1. 



