IV. PREFACE. 



A great difficulty has been to know how to deal with those forms 

 which have been in some manner introduced. I have been severely 

 criticised on this point already. First, if I had taken only absolutely 

 native or indigenous plants, I should have departed from the course 

 pursued by every other author of a local Flora, and been very severely 

 blamed for carelessness in not doing the work thoroughly. Secondly, as 

 I have admitted every species now found established in a wild condition, 

 however introduced, I shall be of course exposed to those who say that 

 only well established plants should be admitted in a local Flora. 

 The criterion I have taken is the establishment in a healthy condition 

 of self-sown plants. None other is really of value, and certain interest- 

 ing problems could not have been studied, if these doubtful forms had 

 not been included. The climate of the county is so genial, that these 

 introduced plants are exceedingly abundant, and exceedingly difficult 

 to tell from plants undoubtedly native to Scotland. I do not know of 

 any other method of treating this question, which does not either on the 

 one side or on the other involve serious error. 



In citing localities I have tried to pass, in the case of Maritime 

 Plants, from the Mull of Galloway, along the coast of Glencaple, and 

 thence to the English Border. The three great valleys are then taken 

 in order, and the reader is supposed to pass up the Western and down 

 the Eastern bank. Further subdivision than that here given did not 

 seem to me of any practical use. The Cargen, Cairn, etc., are in- 

 dubitably part of Nithsdale, just as the M and Kirtle are quite 

 characteristically Annandale. 



Of course no work of this nature can ever be complete. The 

 London Catalogue shows a considerable growth in two years, and is still 

 growing. I have chosen to produce this work as it stands, partly because 

 the information is quite correct and will undoubtedly be of assistance, 

 and partly because six years of African travel has greatly told on 

 pedestrian efficiency, and I know that it could not be appreciably 

 improved by my own exertions. 



The amount of assistance received from my local friends will be 

 visible to all those who read the Flora. I must thank all heartily for 

 their kind and valuable help. Perhaps one of the pleasantest remem- 



