DISTRIBUTION OF SPHAGNUM AND CAREX 337 



flora of those countries." Doubtless birds have played the principal 

 part in the dissemination of species along this route; but the high- 

 lands of the Greater Antilles evidently serve as halting-places in the 

 track of migratory birds across the Caribbean Sea. In his descrip- 

 tion of the dispersal of Uncinia by birds, which is quoted in Note 37 

 of the Appendix, Morris states that migratory birds on their way 

 north and south between North and South America rest on the high- 

 lands of Jamaica at elevations of 5000 to 6000 feet above the sea; 

 and so exhausted are they that they can be caught with the hands 

 (Nature, December 16, 1886). 



The Stream of Plants from the Far North down the Andes 

 to Cape Horn. — The stream of species from high northern latitudes 

 in North America down the Andes to Cape Horn is well illustrated 

 both by Sphagnum and Carex. They are all species that are distributed 

 round the pole in the Arctic and Subarctic regions, both of America 

 and Eurasia. Half of the species of Sphagnum and a third of the 

 species of Carex that have been found south of the Straits of Magellan, 

 that is, in Fuegia, are thence derived. Whilst the main stream from 

 the north follows the line of the Andes, the outside regions have caught 

 the eddies ; and, as in the case of Sphagnum in South Brazil, where 

 only 3 per cent, of the species occur outside South America, the 

 endemism is intense. Some of the principal conclusions here drawn 

 with reference to the southward trend of Sphagnum and Carex in 

 South America are exemplified in the following table ; but naturally 

 there is much that can be substantiated only by reference to the 

 original memoirs of Warnstorf and Kukenthal. 



Table illustrating the Concentration in the Southern Part op South 

 America op Arctic and Subarctic Species of Sphagnum and Carex 



THAT ARE BOTH EURASIAN AND NORTH AMERICAN 





Total number of 

 known Species 



The North American and Eurasian Species 



Number and Per- 

 centage 



Distribution in the North 





Sphagnum 



Carex 



Sphagnum 



Carex 



Sphagnum 



Carex 



South America 



110 



81 



6=6% 



11 = 14% 



Five species 

 are Arctic 

 and Sub- 

 arctic and 



one is 

 Temperate 



Eight 

 species are 

 Arctic and 

 Subarctic 

 and three 

 are Tem- 

 perate 



Andes only 



25 



51 



4 = 16% 



11=22% 



Patagonian 

 Andes and 

 Fuegia 



8 



30 



4=50% 



11=37% 



(A) As illustrated by Sphagnum. — Let us begin with the South 

 American species of Sphagnum. Out of about 110 species, at present 

 known, only six have been found outside the New World. They are 

 S. fimbriatum, plumulosum, mexicanum, pulchricoma, torreyanum, 

 and medium ; and of these five are Arctic and Subarctic species, 

 found in all cases both in Eurasia and North America. Four of them 

 reach the Patagonian Andes, and three extend across the Magellan 

 z 



