276 



DR. HOOKER ON THE DISTRIBUTION OF ARCTIC PLANTS. 



Tlie Froportion of largest Orders to the whole Flora. 



o 



Arctic Flora 



„ Europe 



,j Asia 



„ W. America. 



,, E. Am«rica . 



,, Greenland.. . 

 All Greenland . . . . 



1 : 5-C'l :S0-5 1 : 502 1 :27-l|I :33-l!l: lOO'l :26-2ll: l/'Sl 

 1 : 5-21: 38-4 1 : 56-0,1 : 23-7,l : .30-8 1 : 12-3!l : 34-2!l : 21-2 1 



1:10 

 1: 6 

 1 : 5 

 1: 3 

 1 : 3 



Gil : lG-6 1 : 23-3 1 

 71:24-3!l:52-01 

 8|l :27-0il :76-0|l 

 8jl:29-6,l :51-7,1 

 71 : 34-0 1 : 42-71 



16-6,1 : 21-2 1: 

 33-0 1 :22-7;i : 

 ;34-5|l :23-7il; 

 ; 23-0 1 : 17-3 1: 

 : 24-91 :21-4jl; 



9-6 1 : 

 9-6 1 ; 

 10-5 1 ; 

 20-71 

 15-0 1 



15-51 

 19-1 1 

 21-0|1 



17-2il 

 27-21 



24-6,1 ; 



30-8|l; 



29-l'l; 



28-0'l; 

 : 27-0,1: 

 ; 207-011 

 ; 149-6 1 



15-0 

 15-4 

 14-5 

 15-9 

 17-2 

 10-3 

 12-4 



14-1 



17- 



11-6 



18-9 



11-91: 



10-9 1 



12-01 1 



17-7 

 24-6 

 21-2 

 17-3 

 18-9 

 23-0 

 27-2 



The great differences between these proportions show how little confidence can be 

 placed in conclusions drawn from local floras. EricecB is the only order which is more 

 numerous proportionally to other plants in every province than in the entire arctic flora, 

 and Cruciferoi is the only one that approaches it in this respect ; and LegimiinoscB is the 

 only one which is less numerous proportionally in them all. East and West America 

 agree most closely of any two provinces ; then (excluding Legiiminosce) all Greenland 

 and Europe; next Arctic Greenland and all Greenland. 



The greatest differences are between Arctic Europe and Asia, and Arctic Asia and 

 West America ; they are less between Arctic Greenland and Asia (excluding ie(/w«iMiOs«) ; 

 they are great between Arctic Greenland and East America ; and as great between all 

 Greenland and Arctic America. 



The proportion formerly deduced by Brown, &c., for the high arctic regions was a 

 much smaller one ; the Monocotyledons being in comparison with the Dicotyledons 1:5; 

 and this still holds for some isolated, very arctic localities, as North-east Greenland ; 

 whereas Spitzbcrgen presents the same proportion as all the arctic regions, 1:2-7; the 

 Parry Islands 1:2-3; the west coast of Bafiin's Bay, from Pond's Bay to Home Bay, 

 1:3-3; and the extreme arctic plants mentioned at p. 257., 1:3. Of the prevalent arctic 

 plants mentioned at p. 256, the proportion is 1 : 3-f. 



I have dwelt more at length on these numerical proportions than their slight impor. 

 tance seems to require ; my object being to show how little mutual dependence there is 

 amongst the arctic florulas. Each has profited but little through contiguity with its cq- 

 terminous districts ; though all bear the impress of being members of one northern flora. 



On Groujnng the Forms, Varieties, and Species of Arctic Flarbts for purposes of 



Comparative Study. 



Considering the limited extent of the arctic zone, the poverty of its flora, which is 

 almost confined to 14° of latitude in the longitudes most favourable to vegetation, and. to 

 only 10° in the Asiatic area, and the number of able botanists who have studied it, it 

 might be supposed that the preliminary task of identifying the species, and tracing their 

 distribution within and beyond the arctic circle would have been short and simple ; but 

 this is not the case ; for owing to the number of local floras, voyages, travels, and scientific 

 periodicals that have to be consulted, to the variability of the species, and the consequent 

 difficulty of settling their limits, and to the impossibility of reconciling the divergent 



