LAWSON ON CANADIAN SPECIES OF RUBI. 365 



to vary in the wild state, and the consequent difficulty of deter- 

 mining what are really distinct permanent species as distinguished 

 from varieties. This is particularly the case with regard to the 

 European Huhi fruticosi, many of the long recognized species 

 of which are so closely related that some of our best botanists now 

 rank upwards of twenty forms, too well marked and too constant 

 to be mere varieties, as so many '* sub-species," under the specific 

 type of Rubus Jriiticosus. The European Raspbeny, R. Idasus, 

 stands out from them all, a solitary, isolated species, that has 

 no intimate relation to any of them, and no tendency to vary 

 in their direction. In fact the relatives and derivatives of this 

 species are to be sought for out of Europe. It is known to be 

 spread over the whole north of Europe and Asia, even so far as to 

 Mandschuria and Japan, but to be absent from the American 

 Continent. Here we have its representative so called species, R. 

 strigosus, our common raspberry, while this and other Canadian 

 species have their representatives in Eastern Asia. As the result 

 of a most elaborate investigation, Mr. F. W. C. Areschoug has 

 arrived at the conclusion that the European raspberry, as well as 

 the North American forms most closely related to it, grew primitively 

 in Japan and adjacent countries. (^Botanisha JSTotlser, 1872, 

 a7id Journal of Botany, 1873.) 



The remarkable similarity between the flora of Eastern North 

 America and that of Eastern North Asia, has been prominently 

 brought under notice by Professor Asa Gray long before its true sig- 

 nificence, or the questions which it suggested were fully appreciated 

 by botanists. His views are that our present vegetation in Eastern 

 America, or its proximate ancestry, occupied the arctic or sub-arctic 

 regions in Pliocene times ; that plants of the same stocks and 

 kindred, forming a nearly uniform flora round the arctic zone, (as 

 uniform perhaps as our present arctic flora) , made their forced migra- 

 tion southward upon widely different longitudes, and receded more 

 or less as the climate grew warmer, and different associations of 

 plants thus established themselves in regions suited to them, but 

 not in any other. In the light of Professor Gray's theory, and the 

 special results obtained by Mr. Areschoug, Professor Lawson 

 described in detail the various species of Rubus inhabiting the 



