14 Origin of the British Flora. 



species are more properly desert plants, and are only 

 confined to the coast because in Britain we have no other 

 suitable regions. 



The aquatic flora consists largely of species of wide 

 range, which have a remarkable power of reaching isolated 

 rivers, lakes, or ponds. Though some of these species are 

 confined to limited areas, most of them tend to re-appear 

 wherever the local conditions are favourable. They are 

 apparently more limited in their northerly range by un- 

 favourable climate than by difficulty of crossing barriers. 

 Several of the aquatic plants of limited range are almost 

 confined to the East Anglian broads and rivers ; but this 

 limitation is evidently due to the more extensive and 

 connected waterways of that district, rather than to other 

 conditions. Not one of our aquatic plants is a member 

 of the Alpine flora, or belongs to the Lusitanian group 

 found in Cornwall and in the West of Ireland. 



Among the marsh and peat-moss plants are many of 

 which the local distribution is evidently governed by 

 climate and geographical position, and is not dependent 

 on soil or amount of rainfall. A large group of these 

 plants consists of upland forms, such as the Arctic willows 

 and sedges. Anothersetis confined to the Eastern Counties; 

 though these are few in number, notwithstanding the large 

 area of swampy ground there found. A third group is 

 confined to the South-west of England, or to the West of 

 Ireland. 



The anomalies in the distribution of our peat-moss 

 and marsh plants are very striking, especially as this flora 

 probably has been less affected by human agency than 

 any other, except the Alpine. Man may have drained 

 a certain number of swamps, and thus exterminated some 

 species, principally in the Fenland ; but it is not probable 

 that he has had much to do with the introduction of new 



