Clare Island Survey — Phanerogamia. 1 39 



third symbol deals with the present habitat and its condition ; a natural habitat 

 means one which has never been altered by man. But in certain cases 

 in all three categories, where the interference by man was of early date, all 

 trace of it may now be lost. The lines of investigation to be pursued in 

 attempting to apply these tests to our flora are well put forward by Adams 

 (loc. tit.). 



The only point in which the formula suggested above fails to show 

 completely the standing of a plant from this point of view is that it deals 

 only with the plant's history up to the present, and makes no prediction 

 as to the future— in other words, it does not express whether we believe the 

 plant to be established in its habitat, and likely to remain there indefinitely 

 without the assistance of man (as is the case with natives and naturalized 

 aliens) — or whether we believe the plant likely not to endure, as in the case 

 of the majority of agrestal species, casuals, &e. When we have an opinion 

 on this subject, we can express probable temporary occupation of the ground 

 by putting in brackets the triple symbol which expresses the plant's past 

 history. 



Of course, this system applies only to any particular individual we 

 choose to select ; and another individual of the same species growing close 

 by may have a different history. A plant which we brand * * * may as 

 a species be N N N in the district all the time. But, it must be remembered, 

 we are dealing with a vegetation much disturbed by man, in which we are 

 endeavouring to distinguish the fragments of the aboriginal flora ; our test 

 is applied to the individuals most nearly native that we can find. A species 

 is set down as native in a district even though ninety-nine out of every 

 hundred individuals may fail to pass the test, so long as there can be no 

 doubt about the hundredth. The various individuals of almost every species 

 in any area divide themselves among several of the categories given above ; 

 the standing of a species is indicated by the applicable formula which most 

 nearly approaches the native standard. 



This method of analysis is not very satisfactory, especially since the Nor* 

 which we assign is a matter of opinion, though founded on what evidence we 

 can gather. It is easy to invent a reductio ad absurd/urn — for instance, is the 

 progeny of a native plant never more to be allowed native rank, because at 

 some time in the past one generation was spent self-sown in a disturbed 

 habitat ? Nevertheless, the method will be found to clarify our ideas as to 

 the standing of plants in a great majority of cases, and large groups of 

 species can without difficulty be assigned their place in the system. Let us 

 return now to the consideration of the flora of Clare Island. 



Maritime Vegetation. — On the cliffs and sea-rocks, as mentioned above, 



