Ixsvi INTEODUCTIOJSr. 



for the first time. Tte observations recorded in the various books 

 and papers quoted from have usually been made by the respective 

 authors of the books or papers. Where exceptions to this rule occur, 

 the name of the observer precedes, in parentheses, the contracted 

 reference to the book or paper ; thus ( 6. M. Kinahan) : Rec. AM. 

 denotes an observation made by Mr. G. H. Xinahan, and first pub- 

 lished in Recent Additions to the Flora of Ireland, in 1872. 



Appendix. — All plants recorded as Irish, but in our opinion 

 not fully entitled to a place in the flora, have been relegated to one 

 comprehensive Appendix. There are some obvious disadvantages 

 inseparable from this arrangement, since it groups together such 

 diverse categories as errors, casuals, escapes, and semi-naturalized 

 species ; but the facility of reference which it secures will, it is 

 hoped, be found to more than counterbalance these disadvantages. 

 In many instances the question whether a plant should take its 

 place in the text or in the Appendix could only be answered con- 

 fidently after a tedious weighing of the often imperfect or distorted 

 evidence : in a few it could hardly be answered with confidence 

 at all, and the final decision merely expresses the preponderance 

 on one side or the other of conflicting sets of probabilities. 



A good deal of historical interest attaches to the first recogni- 

 tion of an alien species which eventually succeeds in winning a 

 permanent place in a flora. But the difficulty of forecasting which 

 of the many candidates for admission may be destined to effect a 

 permanent lodgment is only too obvious. Some subtle mutual 

 fitness between the immigrant species and the complex set of new 

 conditions it encounters in a new country may at any time give 

 rise to an unexpected addition to a flora. Hence it has seemed 

 best in drawing up this Appendix to admit many plants whose 

 prospects of final establishment may at present appear but slender. 

 Along with these, a place has been given to a considerable number 

 of aliens already semi-naturalized and almost entitled to rank as 

 members of the flora, full details being given as to the present 

 standing of both classes. Attention is thus drawn to the material 

 which may be expected to feed the f utui-e growth of the Wsh flora 

 and to do this must be regai'ded as amongst the chief ends to be 

 .served by this Appendix. 



