Chap. VI] EDAPHIC INFLUENCES IN THE TROPICS 401 



Fig. 2 



si. Sonneratia acida. Javanese mangrove. 

 From a photograph by G. Karsten. 



extensive bushy mangrove (Fig. 222), in which the grey foliage, often 

 bedecked with bright yellow inflorescences, extends nearly to the ground. 

 Aegiceras majus is a moderately 

 tall shrub, and Acanthus ilici- 

 folius a thistle-like herb. 



The stilt-roots, which give 

 Rhizophora mucronata such a 

 peculiar appearance, occur rela- 

 tively strongly developed else- 

 where only in the herbaceous 

 Acanthus. In Rhizophora con- 

 jugata, which does not descend so 

 far towards the sea as does R. 

 mucronata, they are more weakly 

 developed than in R. mucronata. 

 Intheother mangrove-trees they 

 are either absent or only slightly 

 developed (Fig. 225) ; in parti- 

 cular, the anchoring-roots de- 

 scending from the branches are 

 wanting. 



On the other hand, the roots 

 of most mangrove-trees are 

 characterized by the possession 

 of highly peculiar pneumato- 

 phores (Figs. 223, 224, 225). 

 These are displayed in their 

 simplest form by Carapa obovata 

 (Fig. 223, 3), where the serpen- 

 tine creeping roots project above 

 the mud with their upper edge, 

 like the blade of a thick knife, 

 but studded w r ith lenticels. In 

 Carapa moluccensis the secon- 

 dary growth in thickness in the 

 upper part is irregular, so that 

 the root terminates in finger-like 

 outgrowths. In the species of 

 Bruguiera (Figs. 223, 1 and 2 ; 

 225), the horizontal roots here 

 and there bend out of the mud 

 into knee-like structures, which 

 in Bruguiera gymnorrhiza bear large lenticels, but in Bruguiera caryophyl- 



SCHIMPER T_) (J 



Fig. 222. Avicennia officinalis at low tide. Javanese 

 mangrove. From a photograph by G. Karsten. 



