74 NEW ZEALAND PLANTS. 



THE MANGROVE. 



Let us leave the dunes, and, in imagination, sail up one of those 

 wide estuaries in the west of the Auckland Province Hokianga or 

 Kaipara Harbour, or one of the tidal rivers of the east the Wha- 

 ngarei, for instance. If it is high tide, we shall see on either side 

 of the stream, a belt of close-growing, dull-coloured, small trees, rising 

 out of the turbid water. These consist of the mangrove (Avicennia 

 officinatis), and the sight is one almost unknown in any other land 

 outside the tropics. It is, in fact, one of the natural wonders of New 

 Zealand. 



Now, quite undeservedly, the mangrove has got a bad reputation. 

 A mangrove swamp is supposed to represent all that is most 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, and in New Zealand the man- 

 grove belt is quite a pleasing feature of the northern rivers. It is 

 also a most 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 in. or so in length, looking much like stout asparagus-shoots. One 

 might feel sure these were young mangroves. But they are nothing 

 of the sort, strange as it may seem. They are roots, which, instead 

 of passing downwards to anchor the trees, grow upwards into the air. 

 On being examined, they 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. 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 



