2« 
Tanslcy and Fritsch. 
is permanently covered with vegetation. The vegetation of tidal 
mud is of course typically halophilous, since it is periodically 
bathed with salt water. The physiological relations of the plants 
are all profoundly affected by, and are certainly adapted to, the 
presence of large quantities of common salt. This leads, as is well 
known, to various structural features which have much in common 
with those found in xerophilous vegetation. The plant-associations 
inhabiting tidal-mud in temperate regions are exclusively herba¬ 
ceous— in our own country the Salicornia-Glyceria Suaedn 
formation ; in the tropics, on the other hand, a vegetation of 
arboreal habit, the well-known mangrove forest, has been developed. 
3 .—The Mangrove-Formation (Tidal Forest). 
The existence and the chief physiognomical characters of this 
striking vegetation have been known to European botanists 
Fig. 8 . Bniguiera gymnorliiza and Rhizophora conjugata on the banks of the 
Bentotta river. 
A group of the former in the foreground shews the short stilt-roots 
fused with the base of the trunk. Knee-roots are seen emerging 
from the mud on the right. Behind is a tree of R. conjugata sending 
very long branches supported by stilt-roots over the edge of the water. 
(After a sketch by Dr. W. H. Lang). 
