HAMIIvTON SCIENTIFIC ASSOCIATION 99 



Notes oi\ Plant Distribution. 



Read before the Hamilton Scientific Association^ 

 March 2Ut, 1907. 



BY A. AI.EXANDER. 



This subject of Plant Distribution, or Geographical 

 botany, as it is sometimes called, is but in its infancy, for 

 the testimony of the rocks is very imperfect, as allowed by 

 the most advanced adherents of the so-called Development 

 theory themselves, and the full value of the Glacial Epoch, 

 which figures so largely in the new view of the history of 

 plant dispersion is full of difficulties, while the plant material, 

 tho' consisting of tons of catalogues of the Flora of nearly 

 every section of the earth's surface, is still in course of 

 arrangement. Nevertheless a very feasible hypothesis has 

 been launched, and many able men have devoted long lives to 

 the study of the subject. Among these I may mention 

 Bentham, Hooker, Darwin, Asa Graj^ and many others. 



The earliest scientists who studied the vegetable covering 

 of this globe of ours, took it for granted that the various 

 species of plants were created where they found them, and 

 that they were placed there because the environment was 

 what they needed. They did not take into account the effect 

 of long ago geological upheavals and changes of temperature. 

 The only treatise published before Darwin's researches was 

 that of De Candolle, who mapped out the surface of the 

 earth into about twenty stations characterized by plants 

 indigenous to these stations. Of course in each of these there 

 are many species common to many or all of the others. 



The distribution of plants is, generally speaking, more 

 independent of other classes than that of animals. It has 

 been well stated that the supply of food is one of the great 

 causes regulating the diffusion of a race. Animals feed 



