4i6 



INTRODUCTION TO PLANT GEOGRAPHY [CHAP. 



free from snow in summer and widely favourable for plant life, the 

 Antarctic Continent is permanently ice-covered except for very 

 limited areas chiefly about its borders. Here the ice and snow may 

 disappear for a brief period in the most favourable season and allow 

 some depauperated, almost entirely cryptogamic, vegetation to grow. 

 A few ' oases ' up to a reputed 300 or so square miles in area have 

 been reported in recent decades to occur at varying distances inland, 

 though mainly near the coast. They are largely free from snow 



Fig. 139. — Crustaceous and foliose Lichens on rocks near shore, Goudier Islet, 

 Antarctica. From these rock faces, especially where attacked by Lichens, and 

 from marine and wind-borne debris, there may accumulate in crevices and depres- 

 sions a fair soil on which fruticose Lichens and Mosses often grow. (Phot. 

 I. M. Lamb, courtesy of Falkland Islands Scientific Bureau.) 



in the favourable season and are reported to have lakes green with 

 Algae but to be otherwise devoid of evident life, though apparently 

 they have not been scientifically investigated. Many rock faces 

 even well away from the ice appear entirely barren, at least from a 

 distance, though in some places especially near the shore a fair 

 growth of crustaceous Lichens may be found ; here there may be an 

 accumulation of soil, and, growing on it, fruticose Lichens and Mosses 

 (Fig. 139). This poverty of the antarctic vegetation especially on 

 the Continent must be related to the very unfavourable climate — 



