344 PLANTS, SEEDS, AND CURRENTS 



the continent, North Africa being regarded as European in a floral 

 Bense. These are indicated in the table below given. 



The Distribution of the non-Endemic African Species of Sphagnum (6) 



and Carex (7) 





Sphagnum 



Carex 





North Africa 



— 



4 



Included in the European floral region. 



Eurasia 



— 



6 



For Carex, Europe, 5 ; Asia 5. 



North America 



1 



1 





South America 



1 



1 





Australia and New 

 Zealand 





2 



For Carex, Australia, 1 ; New Zea- 

 land, 1. 



Madagascar and the 

 Mascarene Islands 



5 



1 



For Sphagnum, Madagascar, 3 ; and 

 Mascarene Is., 4. 



Amsterdam Island 



1 







Teneriffe 



1 







The outside Connections of the African Peat-mosses. — The 

 Sphagnum connections beyond the continent first claim our attention. 

 Of thirty-one species recorded from Africa, as geographically here 

 defined, only six form connections with the outside world, four-fifths 

 of the species being endemic. Of the six concerned, four merely link 

 the continent with Madagascar and the Mascarene Islands (Bourbon, 

 Mauritius, and Rodriguez); one of them, S. pappeanum, occurs 

 on Bourbon and Rodriguez, on Teneriffe, and on Amsterdam, an 

 island in the centre of the Indian Ocean; whilst the sixth, S. pul- 

 chricoma, is a characteristic North and South American species that 

 has only been recorded in Africa from the Tanganyika district. 

 The limited nature of the external connections of the African 

 Sphagnum flora is thus apparent ; and it serves to emphasise the view 

 that Africa stands first among all the great continents as respects the 

 isolation of its Peat-mosses as well as of its Carices. 



It is noteworthy that eighteen of the thirty-one African species 

 of Sphagnum belong to the subsection Subsecunda, the largest and 

 most differentiated of all the ten subsections of the genus and holding 

 one-third of the species. Though it has active centres of differen- 

 tiation in all the great continents and is more uniformly spread over 

 the world than the other subsections, these centres are not connected 

 by world-ranging species. Not one of the ten species of Sphagnum 

 possessing the widest ranges belongs to the subsection Subsecunda, 

 and not one of them is African. This isolation of Africa must be 

 associated with the circumstance that the majority of its species 

 belong to a subsection that is practically closed to the outside world. 

 A further implication of this fact will be noticed below. It will be 



