1898-99.] 485 



country as the plant is dioicous, and only the female plant is 

 found here. In the new edition of Cybele Hibernica it is 

 stated to be gradually decreasing throughout Ireland, a fact 

 which will be welcome news to mill-owners, if it turns out to 

 be correct. Another alien also of a troublesome character was 

 described — the rough hawk's beard, Crepis biennis, hailing this 

 time from Germany. Probably imported with grass-seed, 

 since 1880 it has increased to such an extent as to spoil the 

 hay in wet meadows. Here was work for the proposed Board 

 of Agriculture in taking measures to stop the spread of this 

 weed, and see chat imported grass-seed was free from its seeds. 

 A natural plant society is one which can maintain itself. 

 Such a community as springs up on a garden plot or along 

 a newly made railway is unnatural, in the sense of not being a 

 well-proportioned and self-supporting community. In a short 

 time the weeds and casuals will take their departure if left to 

 nature, and a natural and well-balanced community will take 

 its place, such as we find on undisturbed ground, or in an old 

 meadow. Environment has, of course, much to do with the 

 character of the plant society of a place. The bog, the wood ? 

 the mountain, have special plants of their own which we find 

 associated. The rocks have an important influence on the 

 flora, and North-East Ireland has a most interesting community 

 of plants for this reason, that it contains such a variety ot 

 rocks. Mosses are an even better guide than seed plants to 

 the kind of rock on which they grow, and a bryologist ought to 

 be able to tell the kind of rock from the mosses which grow on 

 it. There is a striking difference between the basaltic and 

 limestone flora of County Antrim, and the silurian or granite 

 flora of County Down. 



At the close of the lecture Mr. J. H. Davies was requested 

 to make some observations on the recently published second 

 edition of Cybele Hibernica by Mr. Colgan and Dr. Scully. 

 He thought that some indication of the spirit by which they 

 had been animated might be found in the quaint words of the 

 amiable Caleb Threlkeld, written in the early part of last 

 3 



