420 INTRODUCTION TO PLANT GEOGRAPHY [CHAP. 



represent a relic from some past age, the plants in the Azorella 

 community are all more or less xeromorphic. Those of the Acaena 

 community, on the other hand, are more or less hygrophytic in 

 character, lacking any obvious means of protection against the 

 mechanical and desiccating effects of the wind. Thus from the 

 rampant main axes of this dominant, which form a thin-meshed 

 network on the ground, leafy shoots ascend to a height of often 

 20-50 cm. (about 8-20 in.). In rocky places various F'erns occur, 

 including a Filmy-fern {Hymenophyllum peltatum) and forms of the 

 familiar northern Polypody {Polypodium vulgare agg.) and Brittle- 

 fern {Cxstopteris fragilis s.l.). Limited to the salty beaches are 

 Cotula plumosa and Tillaea moschata. 



The vegetation of the other islands of the Kerguelen Group, such 

 as the Crozet and Prince Edward Islands which extend westwards 

 in comparable latitudes to 38° E. longitude, and the nearer but more 

 southerly McDonald and Heard Islands, does not appear to show 

 any important deviations in its general character from that of 

 Kerguelen Island itself. However, McDonald and Heard Islands 

 tend to be particularly barren, presumably owing to their higher 

 latitude (c. 53° S.). Of the thirty species of flowering plants known 

 from the Kerguelen Group, no fewer than six (20 per cent.) are 

 endemic, the Pringlea (Kerguelen Cabbage) being the sole known 

 representative of an apparently endemic genus. 



Of the islands lying south of New Zealand, Macquarie Island 

 (about 55 S.) is antarctic in character, with few and usually dwarf 

 woody plants (such as Coprosma repens, though the taller Acaena 

 adscendens and an allied species also occur). Wide stretches of the 

 hills are taken over by the yellowish tussocky grass Poa foliosa, 

 between whose tufts occur here and there larger ones of Stilbocarpa 

 polaris and silvery rosettes of Pleurophyllum hookeri as well as two 

 species of Acaena. Azorella selago is reported to form large cushions 

 on the wind-blown summits of some of these hills and to harbour 

 other plants as on Kerguelen. On the rocks of the shore are tussocks 

 of Colohanthiis muscoides, Tillaea moschata, and a small endemic Grass 

 besides the more familiar Festuca erecta. In swampy as in some 

 drier places Poa foliosa is typical, and on the beaches Cotula plumosa. 

 The nearest land is 650 km. away, and as it is considered unlikely 

 that any vascular plants survived the severe Pleistocene glaciation 

 on Macquarie Island, it is thought that migrating sea-birds must 

 have been the main agents of importation of the thirty-five species 

 of vascular plants known to grow on the island — cf. page 114. 



