64 Queensland's plant associations 



which make on some localities a special sub-type of this 

 formation (She oak swamps). We find the adaptation of 

 this association again very interesting. The plants growing 

 here must at one period of the year resist the effects of floods, 

 at another season again they must bear dry weather.. 

 Neither the vine-scrub nor the open forest is able to grow 

 under these circumstances. In the first stage the tea-tree 

 swamps have hardly any undergrowth, the water at the end 

 of the wet season being full of splendid water lilies {Nym- 

 phaea gigantea and others), which seem to disappear in the 

 dry season. Xo other association gives us such splendid 

 opportunity to study the changes in the vegetation a« this, 

 for the conditions change often in a comparatively short 

 time. We can observe in many localities how the tea-tree 

 swamps take, by and by, the chsiracter of forests and at last 

 become permanently so. On the other hand I saw in the 

 district of Cairns different transitions between tea-tree 

 swamps and vine-scrubs. Tea-tree swamps have in the 

 North of Queensland often beside their own plants elements 

 both of the forest and scrub floras. With the change of 

 conditions one of them becomes more plentiful. In Southern 

 Queensland we see regularly slow transitions into forests ; 

 in Northern Queensland, however, where the conditions are 

 more favourable for the scrub plants, sometimes into vine- 

 scrubs. 



A special association is the flora of salt and fresh uater. 

 On marshy, muddy ground near the sea and often in the 

 neighbourhood of mangrove swamps we find sometimes a 

 special association of salsolaceous plants. Near the inlet 

 opposite to Cairns this association is very well developed. 



On many small islands along the Eastern coast of 

 Queensland we observe a strange phenomenon, as some parts 

 of these islands are barren or covered only with grass or 

 other low vegetation, while some other parts are timbered 

 with open forest or sometimes with vine-scrubs. The 

 reason for this strange and very irregular distribution of 

 forest cannot be found in the diii'erent character of soil, as 

 it is to be seen on perfectly identical strata and apparently 

 under quite congruent circumstances. I think, however, 

 that the prevailing winds give us the correct explanation 

 for this phenomenon, as we may observe that the exposed 

 parts of islands, where the air is driei' and the decomposed 



