G9 



XI. On the Origin and Distribution of the British Flora. 

 With an Appendix on the Eiver-basins of Essex as 

 Natural-history Provinces. 



By Professor 0. S. Boulger, F.L.S., F.G.S. 



[Kead at the Field Meeting held at Danbury, August 13th, 1881.] 



Last week will be memorable in the amials of British 

 botanical science. Ten days ago I stood by the open grave 

 of Hewett Watson, who devoted the genius and labour of his 

 life to the elucidation of the geographical relations of British 

 plants ; and two days later appeared the eighth edition of 

 Professor Babington's Manual, — a work that, in its critical 

 discrimination of allied forms, has during the last thu'ty- 

 eight years ably reflected the advance of Botany in England. 



The work of these two men is related to the two divisions 

 of the subject on which I am about to address you. First, I 

 wish to trace the origin of our flora by comparing it with 

 other assemblages of plants ; and secondly, I wish to sketch 

 the distribution of its constituents through the British Isles. 



The most unobservant traveller cannot fail to notice the 

 difference between the plants of one district and those of 

 another. If it may not have fallen to his lot to contrast the 

 luxuriance of a tropical jungle with the barren tundras of 

 Arctic Siberia, or the pastures of our temperate plains with 

 the pine forests of Scandinavian mountain-slopes, or the 

 stunted birches and willows of their summits, he will have 

 seen near his own home that the flowers of the field are not 

 those of the wood, and that those of the sea-shore are not 

 those of the river-banks. 



Such experience leads us all at first to put down the 

 distribution of plants as the effect of differences of climate — 

 using the word in a broad sense ; nor can it be denied that 

 climate is a most important factor in the problem. You will. 



