CHAP. XIII THE CAMEROON/AN SUB-REGION 241 



Moreover, on each of these mountains, the giant groundsels are 

 associated with tree heaths, tree lobeHas, and other plants allied 

 to those of Kilima Njaro and the temperate zones. Teleki's 

 observations did not, however, show whether the Alpine flora 

 of Kenya was more closely allied to that of Kilima Njaro, of 

 Abyssinia, or of the Cameroons, and the determination of this 

 point was one of the main objects of my visit to the mountain. 

 More than half of my collections from Kenya were lost in the 

 Tana, and of the remainder, only two out of three botanical 

 groups have been as yet described. These show that the flora 

 is allied to that of Kilima Njaro, though the species are in 

 many cases distinct. 



The Alpine birds of Central Africa have the same remark- 

 able distribution as the plants, for upon the highest mountains 

 there is an avifauna unrepresented on the adjoining lowlands. 

 Dr. Bowdler Sharpe has grouped together these isolated colonies 

 into a special sub-region, which he calls the " Cameroonian." On 

 his map, illustrating the geographical distribution of birds,^ he 

 shows this "Cameroonian sub -region" as a series of areas 

 scattered over Equatorial Africa. 



The most simple possible explanation of these facts 

 is, that the seeds have been carried by the wind, or by 

 birds, from one mountain summit to another. It is well 

 known that the wind can carry some seeds for enormous dis- 

 tances ; and if the resemblance of the floras of Abyssinia, 

 Kenya, and the Cameroons, were due solely to plants with 

 seeds so small as those of the orchids, or provided with 

 appliances especially adapted for floating in the air, such as 

 the pappus of the groundsels, this explanation might suffice. 

 But seeds so large as those of the Gladiolus, and so hard and 

 heavy as those of Podocarpus, can hardly have been carried far 

 by the wind ; nor are the birds sufficient to account for the 

 distribution, as the sun - birds, which alone occur at these 

 altitudes, are not migratory. 



A second explanation is suggested by the fact that similar 

 anomalies in distribution occur in Europe, where Alpine and 

 Scandinavian plants, such as the little Liizula araiata of the 

 Grampians, live on the summits of mountains, far from the 



^ R. Bowdler Sharpe, "On the Zoo-Geographical Areas of the World, illustrating the 

 Distribution of Birds," Natural Science, vol. iii. (1893), pp. 100-108. 



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