2 DUNLOP, Alien Plants of the Warrington District. 



4. The occurrence of manure-wharves in the vicinity 

 of farms along the banks of the Mersey and 

 the Bridgewater Canal. These places fre- 

 quently produce large numbers of casuals. 



The species herein recorded may be classified as — 



1. Native. 



A species now forming a normal constituent of the 

 flora, and growing spontaneously in the special 

 habitat given. 



2. Denizen. 



A species introduced by some means other than natural 

 dispersal, and " which maintains its habitat," i.e., 

 has become established. 



3. Colonist. 



A species introduced by some means other than natural 

 dispersal, and " which fails to maintain its habitat," 

 i.e., does not become established. 



4. Aliens proper. 



Species introduced by various agencies, and having 



no claim to nativity, and not constituting a part 



of the normal flora. The term includes casuals 



of whatever origin — waifs and strays — garden 



escapes, outcasts, &c. 



In the compilation of this list, I have consulted and 



made use of the late Mr. John Peer's "List of Warrington 



Plants," published in The Phytologist, 1 863. 



Mr. C. R. Billups, of Chatteris, who formerly lived in 

 Warrington, and did a considerable amount of valuable 

 botanical work in the district, has kindly allowed me to 

 include records from his manuscript " List of Warrington 

 Alien Plants." I am also indebted to Mr. Billups for many 

 suggestions and criticisms. 



