DISTRIBUTION OF SPHAGNUM AND CAREX 348 



these results can only be considered as approximate ; but it is prob- 

 able that the effect of future discoveries will be to make the endemism 

 yet more pronounced. The figures, as far as they go, indicate that 

 the intensity of the endemism is greatest in Africa for the Carices 

 and in South America for the Peat-mosses. But by taking other 

 matters into consideration Africa gives promise of standing first also 

 with Sphagnum. Thus, whilst the species connecting both South 

 America and Australia with the outer world often range over much 

 of the globe, most of the African Peat-mosses that extend beyond 

 the limits of the region, as here defined, do not reach farther than 

 Madagascar and the Mascarene Islands. Africa owns not one of the 

 ten or a dozen world-ranging species of Sphagnum. These facts 

 distinguish the continent in a conspicuous manner from both South 

 America and Australia. 



The Necessity of excluding the Insular Element when 

 comparing the sphagnum an© carex floras of continental 

 Regions. — The insular element is removed from this table. The 

 island by the intensity of its endemism is always a disturbing influ- 

 ence in discussions regarding the floras of continental regions. The 

 effect of linking New Zealand with Australia, Madagascar with Africa, 

 and Japan with Eastern Asia, is to produce results quite out of pro- 

 portion to the size of the disturbing area. It has already been pointed' 

 out in the case of Sphagnum that if we included Japan in Asia andi 

 the Malagasy province in Africa half of the known Eurasian species; 

 would be recorded only from Japan, and one-third of the species 

 peculiar to Africa would be found only in Madagascar and the 

 Mascarene Islands. So also with the African Carices peculiar to 

 that region, their number would be increased from twenty-five to 

 forty if we added those restricted to the Malagasy province. As 

 shown in the table for the Australian region given on a later page,, 

 the effect of adding the New Zealand Carices to those of Australia 

 would be to double the number of species. To have employed the 

 combined results for Australia, Tasmania, and New Zealand, in? 

 making the above comparison with South America and Africa,, 

 would have caused a drop in the percentage of non-endemic species 

 from forty-six to nineteen in the case of Sphagnum and from sixty- 

 eight to thirty-four in the case of Car ex. 



Then it should be remembered that with oceanic archipelagos, 

 like the Azores, it may make a great difference in the connections; 

 of a whole continental flora if we link them to a continent with which 

 they have little in common (see Note 22 of the Appendix). The 

 insular factor, in truth, raises considerations other than those specially 

 dealt with in this chapter. It may, however, be remarked that both 

 Sphagna and Carices respond in a similar way to the isolating influ- 

 ences at play in oceanic islands. We find peculiar species of both 

 genera associated on islands in all the oceans, as in the Azores and 

 St. Helena in the Atlantic, in Bourbon in the Indian Ocean, and in 

 Hawaii in the North Pacific. 



We will now look a little closer into the behaviour of the genera 

 Sphagnum and Carex in Africa, more especially as regards the con- 

 nections established by the non-endemic species with regions outside 



