THE MOSSES COLLECTED BY THE SMITHSONIAN 



AFRICAN EXPEDITION, 1909-10 



By H. N. DIXON, M. A., F. L. S. 



(With Two Plates) 



The mosses collected by Dr. Edgar A. Mearns, during the Smith- 

 sonian African Expedition, consisted of eighty-three numbers, of 

 which naturally several were duplicates, the actual number of species 

 represented being forty-eight. As would be expected in the tropical 

 region of Africa, the bulk of them were at high altitudes, only seven 

 numbers being below 2,000 meters, five of these at 1,350 meters, the 

 remaining two at 1,950 meters. Of the rest the largest proportion 

 (between 65 and 70) came from the " giant heath zone " of Mt. 

 Kenia, at about 3,630 meters, five from 4,200 meters, above that 

 zone, and three or four from the " bamboo zone," at about 3,000 

 meters. Only eight species were in fruit. 



A considerable number of the mosses are identical with species 

 already decribed from Kilimanjaro, Ruwenzori, and Kenia itself; 

 quite an appreciable proportion, however, are of especial interest 

 either as being hitherto unknown, or — and these are perhaps the 

 most interesting — as belonging to species already known, but from 

 a very widely distant geographical area. 



A connection between the mosses of the higher zones of the 

 equatorial mountains of Africa and those of the palsearctic region 

 of Europe and North America has been recognized for some time. 

 Mitten, 1 in describing the mosses collected on Kilimanjaro by 

 Bishop Hannington and by H. H. Johnston, refers specimens to the 

 northern species, Bryum roscuin, B. alpinum, and Thuidium tamaris- 

 ciiuim (in addition to two or three almost cosmopolitan species) ; of 

 these the two former at least occur also in temperate South Africa. 



C. Miiller, who has described the greater number of the species 

 collected on Kilimanjaro, fully recognizes the close relationship 

 between the genera of mosses of the higher zones of that mountain 

 and those of the European alpine regions, but his theory of phyto- 

 geography does not admit an actual identity of species between two 

 so widely separated areas, except — and that very rarely — in a few 

 admittedly cosmopolitan types. In the conspectus he has given of 



1 Journ. Linn. Soc. Bot. 27: 298. 



Smithsonian Miscellaneous Collections, Vol. 69, No. 2 



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