338 PLANTS, SEEDS, AND CURRENTS 



Straits into Fuegia. They may, like S. medium, follow the great 

 mountainous backbone of the New World from the Arctic Sea to 

 Cape Horn. This species after extending through the length of North 

 America, from Alaska southward, reappears in the larger West 

 Indian islands, and then travels along the Columbian, Bolivian, and 

 Peruvian Andes at elevations of 10,000 to 11,000 feet, finally reaching 

 Patagonia and Fuegia. Others, like S. fimbriatum, plumulosum, 

 and torreyanum, may skip the tropical regions, and after leaving 

 North America reappear in the Chilian and Patagonian Andes, or 

 not present themselves again until they arrive in Tierra del Fuego. 

 Some, like S. mexicanum, though they may not reach farther than 

 the tropics of South America, exhibit a behaviour very suggestive 

 of their future discovery far south. At home near the sea-level in 

 Subarctic latitudes, this species attains an elevation of from 3000 to 

 3500 feet in the West Indies and Central America, and altitudes of 

 from 7000 to 10,000 feet in the Equatorial Andes. 



(B) As illustrated by Carex. — All that has been said respecting the 

 streaming of species of Sphagnum down the Andes from high northern 

 latitudes can be paralleled in the case of Carex. Thirteen of the 

 eighty-one species described as South American occur outside the 

 New World. Of these eight are Arctic and Subarctic plants that 

 are found in all cases in those latitudes, not only in North America, 

 but also in Eurasia. All of the eight have reached Patagonia and 

 Southern Chile, and six have crossed the Magellan Straits into 

 Fuegia; and it will be seen from the table that, as in the case of 

 Sphagnum, these species from the far north form a considerable 

 proportion of the Carex flora of Antarctic South America. Some, 

 like C. macloviana, may travel with relatively little interruption from 

 the shores of the Arctic Sea down the line of the Rocky Mountains 

 to the Mexican highlands, where this species has been found at an 

 altitude of 14,000 feet, and then along the Bolivian and Chilian Andes 

 to Fuegia. Others, like C. goodenoughii, may extend in North 

 America as far south as Colorado, reappearing in the southern tropics 

 in Bolivia, before proceeding down the Chilian and Patagonian Andes. 

 Some, like C. capitata, range southward from the North- West Terri- 

 tory down the Rocky Mountains, next appearing in Central America, 

 and following the Argentinian and Patagonian Andes into Fuegia. 

 Rut others, like C. microglochin, C. magellanica, and C. canescens, 

 display great gaps in their passage south from high northern latitudes 

 to the Fuegian islands, since they skip the tropics altogether and 

 after following the Rocky Mountains to Colorado next appear in 

 Patagonia and South Chile. The streaming southward is equally 

 well illustrated by species confined only to the New World. Thus 

 C. gayana, after following the whole trend of the Rocky Mountains 

 from Canada to New Mexico, reappears in the Chilian Andes at 

 elevations of 8000 to 10,000 feet before it crosses the Magellan Straits 

 and enters Fuegia. Notwithstanding the gaps, which doubtless will 

 in some cases be filled up by the future investigator, we have here 

 suggestively illustrated the streaming of the Carices down the great 

 backbone of the New World from the shores of the Arctic Sea to 

 Cape Horn. 



