xxxviii INTEODUCTION 



most remarkable of the recent immigrants is a North American 

 .species, Matricaria cliscoidea. Its first appearance was in Dublin in 

 1894. Its range, as at present known, extends from Dublin, Louth, 

 and Armagh on the east coast, to SE. Galway, W. Mayo, and Sligo 

 on the west, and over this wide area it is found, frequently in 

 immense profusion, on roadsides and railways. 



An interesting case of plant-introduction, in which tillage is 

 a secondary cause, may be quoted. The Black-headed Gull breeds 

 in large colonies on lonely and undisturbed bogs, usually on tracts 

 where numerous pools occm', and where a strictly indigenous flora 

 prevails. Its food-supply during the nesting period is drawn 

 chiefly from the adjoining cultivated lands, where it destroys great 

 numbers of grubs and worms. From the tillage, it carries to the 

 bogs a variety of seeds. How these seeds are brought is a point 

 for ornithologists. The bird appears to be only very slightly a 

 vegetable feeder, and from this fact, as well as from the size and 

 nature of the seeds, it seems probable that the majority arrive 

 adhering to the bh'ds' feet. These seeds germinate on the bog, 

 assisted no doubt by the guano, which is probably as beneficial 

 to them as it is inimical to the bog-flora ; and a colony of plants 

 results, strangely out of keeping with its surroundings. The 

 following list of plants, made at one of these bird-colonies in the 

 centre of a large bog near Frankford in King's County, wiU illustrate 

 this case of dispersal ; not one of the plants on the list grew 

 naturally on the bog, which extended unbroken for at least half 

 a mile in every direction : — 



Eanunculus acris. Veronica Chamsedrys. 



Capsella Bursa-pastoris. Y. arvensis. 



Cerastium triviale. Prunella vulgaris. 



C. glomeratum. Plantago major. 



Sagina procumbens. Atriplex sp. 



Trifolium repens. Polygonum Persicaria. 



Epilobium obscurum. Enmex Acetosella. 



Daucus Carota. Juncus effusus. 



Bellis perennis. Holcus lanatus. 



Senecio vulgaris. Pea annua. 

 Hypochseris radicata. 



