Potamogeton undulatus, Wolfga?ig, in Ireland. 125 



History, 1892 (p. 115). I find that a specimen from "Sixmile 

 River, Co. Antrim, 5. 6. 82 (leg.) S. A. Stewart," belongs to it, 

 and seems nearest to the var. Jacksoni, Fryer I.e. p. 290 {P. 

 perfoliatus, L,., var. Jackson^ F. A. Lees of the London Cata- 

 logue). Whether any other Irish specimens are extant I 

 cannot say, as I have not had any opportunity of looking 

 through the British Museum Herbarium or Kew Herbarium 

 for that purpose. 



In Scotland P. undulatus has been gathered in Stirling ! ; in 

 England in Leicestershire ! , Yorkshire ! , Cheshire ! , Salop ! , 

 Anglesea ! , and perhaps Surrey ? ; and it will no doubt be 

 found elsewhere if looked for, or searched for among herbaria. 

 For a very full description, and remarks on affinities, I must 

 refer to Mr. Fryer's paper in the Journal 'of Botany \ 



What is P. undulatus, Wolfgang ? It may be well to give 

 some of the opinions respecting it. Where originally de- 

 scribed in Roemer and Schultes' " Sys. Veg.," Mantissa 3, p. 

 361 (1827), it was considered a sub-species or variety of P. 

 crispus. Ledebour ("Flora Rossica," vol. iv. p. 29 (1853)), 

 seemed to think the same ; as also Eichwald (Nat. Shizz. 

 Lith., &c. (1830)); and as lately as 1890 it appears in Dr. 

 Richter's " Plantae Europoeae " (p. 14), simply as a synonym 

 of P. crispus. In the same year, in Ny man's " Conspectus 

 Florae Europoeae," Suppl. ii., p. 287, it is referred to P. deci- 

 piens on the authority of Schmalhausen. Dr. Tiselius (in Hit.) 

 was inclined to refer it to P. proelongus ; and by myself the var. 

 Jacksoni was considered a form of perfolialus, while Prof. Bab- 

 ington thought it might be a nitens form. This is a suffi- 

 ciently wide reference for certain, taking all the above. Mr. 

 Fryer, by cultivating the form Cooperi, and by a close and 

 careful observance of its various states, coupled with an 

 examination of an original specimen of Wolfgang's, came to 

 the conclusion that it is an hybrid between P. crispus L-, and 

 P. perfoliatus L-, and short of producing it by actual experi- 

 ment, it seems hard to dispute his conclusion. 



The author of the plant, Wolfgang, was a close student of 

 the genus Potamogeton, and drew up a Monograph of it in 

 MS. with descriptions and drawings, and it is to that Mono- 

 graph that the numbers given to Roemer and Schultes by his 

 friend Besser apply. This manuscript is preserved in the 

 Library of the Moscow Society of Naturalists, according to 

 Trautvetter (" Florae Rossicae Fontes," p. 329 (1880)). 



A3 



