Feb. 1903.] BOTANICAL SOCIETY OF EDINBURGH 27 1 



" Topographical Botany " is drawn up nearly within these 

 limits. But even there the limits are not very consistently 

 adhered to. 



To me it seems that more accurate results are arrived 

 at if all plants are included except those known in a 

 district only in cultivation, and that, even of these, the 

 species commonly cultivated in fields and in gardens, in 

 plantations and in woodlands, might with advantage be 

 named in a separate list. The terms " native " and 

 " indigenous " denote only that the ancestors of the plants 

 now living in any locality arrived in it, so far as we 

 know, without man's aid, by what we call natural agencies; 

 for we have no evidence that any species in the Linnean 

 sense is really indigenous in Britain, though certain 

 varieties and " critical species " (in such genera as Rubus 

 and Hieraciiiiii) are not yet known from elsewhere. Man 

 has profovmdly modified the British flora even as regards 

 these " natives," and has admittedly brought into our 

 islands a number of species that are included without 

 question in our lists ; while a good many that appear to 

 be " native " in certain districts have in others evidently 

 been introduced by man. The question really becomes 

 narrowed down to the period when they were introduced, 

 intentionally or otherwise, by man ; but the time of 

 introduction scarcely appears to warrant so absolutely 

 different a treatment as the inclusion of some and the 

 exclusion of others. Man's agency must be recognised 

 as a cause of great changes in the floras of the world. 

 It is in a sense one of the natural forces that modify 

 the vegetation of the world ; and the difference between 

 the action of unconscious forces and the conscious agency 

 of man, though great in degree, should scarcely be reckoned 

 as one of kind. Moreover, man's aid in the migration of 

 plants is often as unconscious as any of the natural forces. 

 Is it not desirable to include all, as above suggested, in 

 the local list, and, as far as possible, to ascertain and 

 to record by what agency, and at what period, each has 

 reached Scotland ? Eecords do not exist of a kind such 

 as to permit of our ascertaining whether species may 

 not have been introduced, even within recent times, apart 

 from man's aid. 



