36 NEW ZEALAND PLANTS. 
hideous on earth—alligators in crowds, a fearsome odour, crabs 
waiting to pick such of the victim’s bones -as are left by the 
alligators, malaria, and deadly “ microbes” in vast abundance. 
Even in the tropics this picture has been shown to be absurd, but 
in New Zealand the mangrove belt is quite a pleasing feature of 
the northern rivers. The mangrove is also a beneficial plant, as it 
materially assists in turning muddy useless shores into good dry 
land. 
Moreover, the mangrove is one of the most noteworthy plants 
in nature. As our boat proceeds up the river the tide has turned, 
and the slimy flats where the mangrove is rooted come into view. 
There, projecting out of the mud, are thousands of upright bodies, 
6 inches or so in height, looking much like stout asparagus-shoots 
(fig. 20). One might feel sure these were young mangroves; but 
they are nothing of the sort, strange as it may seem: they are, in 
fact, roots which, instead of passing downwards to anchor the trees, 
grow upwards into the air. On beimg examined, these erect roots 
are found to consist largely of a very porous tissue. Plants, like 
animals, cannot live without oxygen. They need to breathe just as 
much as we human beings do; without air they would die of 
suffocation, nor would they get energy to carry on their work. 
In the soft mud is little of the life-giving gas, hence the necessity 
for the mangrove to obtain a supply for its ordinary roots. This 
it does with these erect organs, which are the veritable lungs of the 
tree. Of course, the aerial parts of the mangrove, like those of 
any other tree, procure oxygen by means of the small pores in the 
leaves and minute openings in their bark. 
The mangrove, too, has another peculiarity of even greater interest 
than that just described. If a seed were to fall on the muddy floor 
of a tidal estuary, being washed hither and thither by the ebb and 
flow of the tide, it would have little chance of germinating. While 
still on the tree, however, the seed has germinated. The little 
mangrove (embryo) has emerged from its seed-coat, awoke from 
its heavy sleep, and become a fair-sized seedling plant with rudi- 
mentary roots. At this stage it somewhat resembles a broad-bean 
which has just germinated. Therefore it is not a seed which falls 
from the tree, but a young growing plant, whose roots rapidly 
increase in length, pass downwards and outwards from near the tip 
of the stem below the seed-leaves, and anchor the plantlet firmly in 
