200 



Cliff Vegetation. — The word "clifi" is liere used to in- 

 clude the various types of slope rising from the sandy beach 

 and granite platform of the island to the roof. In most places 

 these slopes are not steep enough to be termed cliff in the 

 ordinary sense of the word, especially where they are sandy; 

 but in others, where they are formed of a denser clayey 

 material, the slope is too steep to be climbed easily. It is 

 convenient to use the term cliff, with the reservation as above, 

 when speaking of those sandy slopes from the roof to the 

 shore, which are composed of consolidated sands, to dis- 

 tinguish them from the blown sand on which the littoral 

 flora is developed. 



It was not possible to distinguish any special associations 

 on these areas. The flora they bear is essentially the same as 

 that of the roof 'adjoining, but growing under more exposed 

 conditions. The most frequent type of vegetation is a com- 

 munity with Mesemhryanthemum australe dominant (pi. x., 

 fig. 2). This is often a monospecific community, especially on 

 the exposed faces of the south coast. Mesemhryanthemum 

 australe grows commonly on the mainland at the margins of 

 salt swamps (in distinction to M esemhryanthemiim aequila- 

 terale, which is psammophilous), and its dominance on these 

 exposed cliffs suggests that they are often wetted by spray 

 during high winds. On faces less exposed to spray Mesem- 

 hryanthemum australe grows with Frankenia pauciflora . The 

 impression was gained that the relative proportions of these 

 plants offered some rough idea of the degree of exposure and 

 consequent salinity of the soil at the spot. 



Salsola kali was found toi be dominant, and often the 

 only plant, on some cliff slopes where the sand was less con- 

 solidated. The cliffs of the north coast, especially on Eastern 

 Franklin, show greater diversity of flora. It is probable that 

 here, the exposure to spray and wind being less, the soil factor, 

 with its consequent effect on drainage and aeration of roots, 

 has more play. The communities observed were all open, but 

 it was possible to recognize more than one type. On steep 

 slopes, where the sand was mixed with some amount of clay, 

 Nitraria, M esemhryanthemum australe and Frankenia fruti- 

 culosa were most abundant, Threlkeldia, Fnchylaenu^ and 

 M esemhryanthemum, aequilaterale also being present. At one 

 point a small landslide had taken place recently, and Mesem- 

 hryanthem^um australe and Frankenia fruticulosa were noticed 

 as first colonists of the newly-disturbed ground. 



Where the cliff face was more sandy (pi. x., fig. 1), 

 Scaevola, Myoporum, and Olearia develop with Mesemhryan- 

 themum australe, Threlkeldia, and Frankenia fruticulosa as 

 ground plants. It is probable that in such places Scaevola, 



