lO 



POTAMOGETON PENSYLVANICUS IN ENGLAND.. 



A BENNETT, F.L.S. 



Croydon. 



In November Dr. C. C. Vig-urs, of Newquay, Cornwall, sent 

 me some specimens to look over, gathered by his sister. Miss 

 A. Vigours, in Yorkshire. My surprise was gTeat when I found 

 among- them three sheets of the above Pondweed, a well-knowa 

 one of North America. Dr. Vigurs wrote, ' the Pondweed I can 

 make nothing of.' I at once wrote to Dr. Vigurs, telling- him 

 it was new to England, but reserving the name and country. 

 M asked if it was near a mill, etc' He replied, 'Miss A. E. 

 Vigurs gathered the Potamogeton herself (having- no previous 

 knowledge or information about it) on July 4th, 1907. It was 

 growing in the canal at Salterhebble Bridge, near Halifax, just 

 where the effluent from a cotton spinning mill enters the canal. 

 The canal is cleaner here than elsewhere, and the vegetation 

 more luxuriant. It is (here) five to six feet deep ; Potamogeton 

 crispusy Elodea, a Ceratophyllum^ Glyceria aquaticay and Alisma 

 plantago were growing with or near it. The only Pota?nogeto7ts 

 recorded in Crump and Crossland's ' Flora of Halifax ' are 

 crispus, natans, ohtusifoliuSy pusillus, and pectmatus, Miss 

 Vigurs in litt. 



The history of this species in North America is one of many 

 names. The earlier American authors called it P. hctcrophyllus. 

 Dr. Gavin Watson, 1841 ! Rugel (who collected largely in the 

 southern States), P. fliiitans Auct Am., Carolina, 1842 ! these 

 specimens are the oldest I know in Europe except one in the 

 Delessert Herbarium at Geneva gathered by Rafinesque named 

 P. fluitansy but with no date. He wrote on the North American 

 species in 1808, 181 1, and 1817, and the specimen will probably 

 be between these dates. It was not till Prof. Tuckerman took 

 up the study of the genus that anything like order was evolved 

 among them. He gave a long description of the species, nam- 

 ing it P, Claytonii (after Clayton, who lived in the time of 

 Linnaeus). So it remained for many years, until the year 1885, 

 when Dr. Eichler, of Berlin, kindly sent me the Potamogetons of 

 Wildenow's herbarium. Here I find under No. 3192 three 

 specimens of Tuckerman's plant named P, pcnsylvaiiicus^ with a 

 note by Tuckerman, ' Spec tria superioria pertinet P. Claytoniiy 

 C. Tuccyman E.T.' The description of this was in Linnsea II. 



Naturalist. 



