1 24 The Irish Naturalist June, 



Hooker and Aruott, the authors of the British Flora^ con- 

 sider a plant to '' be trul}^ indigenous where it fortuitous!}^ 

 presents itself." 



Dunn, in his Alien Flora of Britain, uses the following defi- 

 nitions : — 



**A species which exists in perfectly wild and natural vSurroundings 

 both here and in the neigh bonriug parts of the world is deemed indigen- 

 ous." 



" A species will not be considered a native of Britain which is not 

 known in at least one natural habitat, nor even then if it can be shown, 

 by geographical or other arguments, that it was introduced thither ])y 

 artificial means or from an artificial source." 



" The term alien is used to designate any species which, though now 

 spontaneous, originated in Britain through human agency." 



Finally, Woodruffe-Peacock states that — 



'« Man has been the predominant factor so long in any old country 

 like Kngland, that the terms "aboriginal,'' "native," or "indigenous,'' 

 used of modern conditions, simply lead to mental confusion instead of 

 perspicacity in definition"; and that "in England there is nothing 

 natiualWyow exclude human influence." 



lu vay judgment we have still in Ireland many habitats for 

 plants that might fairly be described as " natural," over which 

 man has had no influence, or so little as not appreciabl}^ to 

 affect the distribution of the plants growing therein. Such 

 are the long ranges of cliffs occurring around many parts of 

 the coast, as well as inland escarpments, the precipitous sides 

 of many glens, parts of some of the more extensive bogs, the 

 floor of many lakes^ and small islets occurring therein, and 

 here and there bits of the primeval forest. There are also 

 large tracts of mountain and moorland over which the grazing 

 of sheep and cattle has had but slight effect — at an}- rate I 

 think it will be found that few, if any, species have become 

 extinct in consequence, although their actual distriluition may 

 have become modified. 



In order to avoid confusion it will be necessarj^ to attach a 

 definite meaning to the terms emploj^d. A "native " .species 

 is one that existed in the countr}^ prior to the advent of man, 

 or, if introduced since, has not been introduced b}- human 

 agenc}^ directly or indirectly. An introduced or "alien" 

 species is one that has been brought into the country by man 

 intentionally or accidelltall3^ 



