ANTARCTIC PLANT GEOGRAPHY 349 



lodge on . Moreover, only at that season does the Antarctic anticyclone 

 retreat sufficiently to allow the westerly winds to touch at times the 

 rim of the continent. No doubt sub-Antarctic islands like the South 

 Sandwich Islands, Kerguelen, and the Heard Islands helped in the 

 process by acting as sources of supply for the continually migrating 

 flora, which lodged on these islands in its passage. 



Former land connections cannot be held responsible for the present 

 Antarctic flora, since there is abundant evidence that they disappeared 

 before the last great extension of glacialism in the Antarctic which 

 must have effectively destroyed every vestige of vegetation. It is 

 of interest to note that the phytoplankton of the Antarctic seas is 

 almost wholly distinctive from that of the Arctic seas in spite of the 

 prevalence of diatoms in both and the great similarity of physical 

 conditions. Even in various parts of the Antarctic seas considerable 

 differences have been foundi 



Sub-Antarctic Vegetation^* 



' The vegetation of South Georgia, the Crozets, Heard, Kerguelen, 

 Macquarie, and other sub-Antarctic islands is a form of poor tundra 

 more closely covering the lower ground than in the Arctic islands 

 but much poorer in species. Mosses and peat bogs are numerous, 

 while, owing to the low temperature and high winds, there are no 

 trees. Among higher plants tufted species flourish best, no doubt owing 

 to their power to resist the cooling influence of winds. On many islands 

 tussock grass grows high and luxuriant, giving an impression of rich 

 vegetation. The term "sub-Antarctic" is justified rather by prox- 

 imity to the Antarctic than by any real approximation to Antarctic 

 conditions. The true Antarctic climate is typically continental in 

 contrast to the climate of these sub-Antarctic islands, which is es- 

 sentially oceanic and in most aspects cool-temperate rather than polar. 

 In fact, were it not for the prevailing strong winds, the vegetation 

 would probably be much richer than it is. 



The flora of these islands must be wholly, or at least, almost 

 wholly, postglacial, which accounts for the poverty of species. South 

 Georgia has 18, Kerguelen 30, and Macquarie Island 34 vascular plants. 

 Many of these species are circumpolar in distribution, and most are 

 of Fuegian origin. Some in Macquarie Island are found in New Zea- 

 land but not in Fuegia. There can be little doubt that the postglacial 



" Carl Skottsberg: The Vegetation in South Georgia (Wlss. Ergebn. Schwed. Sudpolar-Exped., 

 Vol. 4: Botany, Part II, No. 12), Stockholm, 1921. 



idem: Die Gefasspflanzen Siidgeorgiens (ibid., Part I, No. 3), Stockholm, 1905. 



R. N. Rudmose Brown, C. H. Wright, and O. V. Darbishire: The Botany of Gough Island (Scot- 

 tish Natl. Antarctic Exped. Sci. Res., Vol. 3; Botany, pp. 33-34). Edinburgh, 1912. 



T. F. Cheeseman: The Vascular Flora of Macquarie Island (Australasian Antarctic Expedition 

 1911-1914, Scientific Repts., Ser. C: Zoology and Botany, Vol. 7, Part III), Sydney, I9i9- 



C. Chilton: Biological Relations of the Subantarctic Islands of New Zealand: Summary and 

 Bibliography, Wellington, 1909. 



