Manchester Memoirs, Vol. liii. (1909), Av^ 14. 



XIV. On the Occurrence and Distribution of some 

 Alien Aquatic Plants in the Reddish Canal. 



By F. E. Weiss, D.Sc, F.L.S., 



Professo)- of Bo/any hi Ihc University of Manchesler, 



AND 



H. Murray, 



Assistant Keeper in the Manchester Musen/n. 



A'ead Jamiary 36th, igog. Received foi ptthlication, March gfh, igog. 

 With One Map. 



Several interesting communications have been made 

 to this Society during the last few years, by Mr Charles 

 Bailey,* and by Mr. G. A. Dunlopf of Warrington, on 

 alien plants found in Lancashire. For the most part, the 

 aliens described, were terrestrial plants, which owed their 

 introduction to this country, partly to the disposal of 

 refuse and ballast, and partly to the use of corn siftings 

 for poultry food. There are, however, well known 

 instances of the introduction into this country of alien 

 pond and waterweeds, the most prolific of which, is the 

 now ubiquitous American or Canadian Pondweed {Elodea 

 Canadensis) which, growing with remarkable vigour, has 

 in many cases completely filled up ponds and waterways, 



* Bailey Charles. " On the Adventitious Vegetation of the Sandhills of 

 .St. Annes-on-the-Sea, North Lancashire (vice-county 60)." Manchester 

 Memoirs, vol. 47, no. 2, 1902. " Further Notes on the Adventitious 

 Vegetation of the Sandhills of St. Annes-on-the-Sea, North Lancashire 

 (vice-county 60)." Jhid., vol. 51, no. 11, 1907. 



+ Dunlop, G. A. '' Alien plants of the Warrington District." Man- 

 chester Memoirs, vol. 52, no. 15, 1908. 



April 2 1 si, igog. 



