Clare Island Survey — Phanerogamia. 10 35 



it has spread by natural means from a natural source." This excludes all 

 interference by man, direct or indirect, as regards either the origin of the 

 seed or plant, its transport, or its subsequent development. But these tests 

 are not easy to apply, and cannot mostly be applied directly. We have 

 to rely rather on the absence of any evidence of introduction, making 

 " native," in its application, a purely negative term, as Watson has 

 pointed out ;' and certain plants early introduced by man may now display 

 no jot of such evidence, and be ranked as native. 2 Every plant was 

 introduced to its present habitat by natural or artificial means at some 

 time ; a native plant means to us a plant the record of whose introduction is 

 lost ; but there is every reason to think that in the vast majority of cases 

 these " introductions " of native species took place before the beginning of 

 man's activities. The only positive evidence that we can hope to obtain of 

 the " nativeness " of a plant is the discovery of its fossil remains in beds of 

 pre-human age ; and on this subject the evidence is only beginning to 

 accumulate. 



From the strictly native species we have a long series, descending to the 

 habitual and confirmed weed, introduced from cultivated land by human 

 hands into cultivated land ; the various grades being well discussed by 

 De Candolle, 3 and exemplified from the British flora by Watson. 4 



In the majority of English floras, " native " is not used in so strict a 

 sense as that quoted above, and generally includes individuals of species 

 truly native in the district or county, growing in either native or artificial 

 habitats 5 ; and in view of the fact that these two categories include between 

 them the range to which the native plants have spread by natural 

 dissemination, there is a good deal to be said in excuse for the practice; 

 though, I think, the only logical definition of the term " native " is the one 

 given above. 



The extent to which human agency has interfered with the vegetation is 

 shown by the fact that Dunn's "Alien Flora of Britain " contains 924 species 

 which that writer looks on as sometimes or always introduced. The greater 

 man's activity in any area, the larger will be the percentage of non-native 

 plants, and vice versa. The true natives mostly shun man's proximity, and 

 increase as we leave his works behind. In fact, if we divide our flora roughly 

 into " anthropophobes " and " anthropophiles," we shall find that the former 



1 H. C. "Watson : Cybele Britannica, iv., p. 65. 1S59. 



2 See A. de Candolle : Origin of Cultivated Plants (English edition), p. 10. 



3 A. de Candolle : Ggographie Botanique Baisonnee, ii., pp. G06-611. 1855. 

 i Tom. cit., pp. 71-77. 



5 An entertaining discussion on meanings of the word native, by an anonymous writer, appears in 

 The Phytologist, N.S. i., p. 93. 1S55-6. 



E 2 



