344 POLAR PROBLEMS 



reproduction. They are more at home in Fuegia, the Falklands, and 

 South Georgia. 



Antarctic Mosses and Lichens^ 



There are no ferns, but mosses are numerous and are in fact one of 

 the chief constituents of Antarctic plant Hfe, in individuals if not in 

 species. Over fifty species have now been described, of which the 

 majority come from the more favored Graham Land and neighboring 

 islands. Many specimens show vigorous and even luxuriant growth, 

 but those from the southern coasts of South Victoria Land in latitude 

 78° are often stunted and puny compared with specimens from Gra- 

 ham Land, fifteen degrees farther north. All Antarctic mosses are 

 frozen solid for a period ranging from eight to eleven months a year, 

 but this does not seem to impair their vitality. They grow in favorable 

 places in small colonies of several species, and occasionally a small 

 tundra of moss and lichen may form a close covering over half an 

 acre or more of ground. The luxuriance of growth in these places is 

 generally due to bird guano supplying nitrogenous matter. Fruiting 

 specimens are rare, and only some six species have been recorded as 

 showing this form of reproduction. Even in the South Orkneys, where 

 moss growth is luxuriant, only one species has been found with any 

 well-developed fruits. 



Hepatics and liverworts are rare. The few that have been found 

 grew in the shelter of moss colonies, mainly in Graham Land. Lichens 

 are numerous, both in species and individuals, and form the pre- 

 dominant feature of plant life on Antarctic land. Many cliffs, even in 

 midwinter, appear gray or orange with thick coverings of Usnea, 

 Placodium, and other lichens, while in summer there is scarcely a 

 bare rock to be seen that has not some growth. Over a hundred species 

 have been recorded, and no doubt more will be found. 



Climatic Causes of Poverty of Antarctic Flora 



The meagerness of Antarctic vegetation and the poverty of its 

 flora compared with those of the Arctic is mainly due to climatic causes, 

 of which the principal is the shortness of the Antarctic summer and 

 its remarkably low temperature. There is no real summer as far as 

 temperature is concerned, for no month has a mean above freezing 

 point. Thus in South Victoria Land in about latitude 78° the mean 



' Jules Cardot: La flore bryologique des Terres magellaniques, de la Georgia du Sud et de I'Antarc- 

 tide (Wissenschaftliche Ergebnisse der Schwedischen Siidpolar-Expedition 1 901-1903, herausg. von 

 Otto Nordenskjold, Vol. 4: Botany, Part II, No. 8), Stockholm, 1921. 



idem: Les mousses de I'Expedition Nationale Antarctique Ecossaise (Scottish Natl. Antarctic 

 Exped. Sci. Res., Vol. 3: Botany, pp. 55-69), Edinburgh, 1912. 



O. V. Darbishire: The Lichens of the Swedish Antarctic Expedition fWiss. Ergebn. Schwed. 

 Siidpolar-Exped., Vol. 4: Botany, Part II, No. 11), Stockholm, 1921. 



idetn: Lichens (British Antarctic ("Terra Nova") Expedition, 1910, Nat. Hist. Repts.: Botany, 

 Part III), London, 1923. 



