38 LINKS WITH THE PAST [ch. ii 



the adaptability of its seeds to dispersal, and em- 

 phasises the importance of the co-operation of 

 botanists and geologists in a common endeavour to 

 trace the origin of British plants. 



In addition to the Pipe Wort, mention may be 

 made of three other American flowering plants 

 recognised in the Irish flora. Sisi/rinchiimi angusti- 

 folium recorded from the west of Ireland is native 

 in temperate North America ; the orchid, Spiranthes 

 romanzoffiana, met with in the south and north of 

 Ireland, is widely spread in Canada and the northern 

 States, while Sisyrinchium californiciiin, a native 

 of California and Oregon, was discovered by Mr Mar- 

 shall in marshy meadow-land near Wexford (26). In 

 the case of the more recently discovered American 

 immigrants, the possibility of human introduction 

 must be borne in mind, though there are no special 

 reasons for doubting that some, as in the case of Erio- 

 caulon, reached the Irish coast by natural agencies. 



