A STUDY OF SEASHORE VEGETATION. 1027 



obvious. The creeping shoots firmly anchored by numerous deeply pene- 

 trating roots offer a much better resistance to the wind and incur much 

 less danger of being torn out of the loose shifting substratum than do 

 erect plants. It is, therefore, no wonder that many other littoral plants 

 adopt a mode of life similar to that of Spinifex, such as Remirea maritime/,' 

 which is almost ubiquitous in the tropics and the still commoner and more 

 widely distributed Ipomea pes-caprm (I. biloba) the extremely long and 

 distantly rooting creeping shoots of which cover and fix the sand in a 

 narrow-meshed net." 



The mangrove plants are specially adapted to growth in heavy muddy 

 soil. The peculiar negatively geotropic roots of Avicennia are its means 

 of securing oxygen for its feeding roots buried in the swampy land. 



The succulents are typical of saline soil, their fleshiness being due to 

 the development of water tissues specially adapted to guard against 

 injurious concentration of salt in the assimilating cells.* 



Considering the number of Avicennia fruits deposited on the shore and 

 the number that had been taken up to the higher part of the beach I was 

 astonished to note how few adult Avicennia plants there were outside the 

 muddy inlet. This may be due to the sand drying after the rains, but it 

 is certainly also due to the fact that cattle wandering along the shore 

 greedily devour the avicennia fruits washed up by the tide. A herdsman 

 told me that cattle and buffaloes do not eat the Ipomea biloba at all. 

 Hence if any change takes place in the vegetation of the areas described 

 we may expect that it will not be an advance and increase of the mangrove 

 plants but mainly of the sand-binders and possibly of the succulents. 



* Schimper : Plant Geography, 1903, p. 89. 



