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called mangrove, that are not true mangroves, and do not belong 

 to the mangrove family. The White "Mangrove" is Lagimcu- 

 laria raceinosa of tropical America. The Black Mangrove is 

 Aviccnnia nitida, also of tropical America, and sometimes called 

 Olive Mangrove. The Mangrove Myrtle is Barringtonia acutan- 

 giita, of the East Indies. The Milky Mangrove is Excaecar'ui 

 agallochuui of Australia. The Tasmanian "Mangrove" is Acacia 

 longifolia. The River Mangrove is Aegiccras inajus, of Indo- 

 Malaya and Australia. 



The American mangrove, which is the species represented in 

 the Hawaiian Islands, is abundant along the coasts of Florida, 

 tropical America, the West Indies, and the Galapagos Islands. 

 It forms vast, monotonous green thickets, and is the van of ad- 

 vancing vegetation along the salt marshes. Its maze of roots 

 make it an effective land builder, and it rapidly gives a foothold 

 to less hardy species. In West Indian waters, for example, man- 

 grove islands are formed so rapidly that in a few years they dot 

 the shallow waters of bays which were formerly destitute of 

 them. 



The tree is round-topped, bushy, and usually 15-20 feet higli. 

 Its branches are spreading, like those of the hau, and its roots 

 make almost impenetrable thickets. Sometimes, in inland situa- 

 tions, the tree grows erect, attaining a height of 70-80 feet, with 

 a fine tall straight trunk, 3-4 feet in diameter, and clear of 

 branches for more than half its length. These trees, of course, 

 yield the best timber. Normally, however, the tree is squat and 

 broad, and as it grows it throws out great numbers of aerial roots, 

 which brace it well on all sides, like those of the Pandanus or 

 Banyan, so that the waves and tides cannot dislodge it. The 

 roots branch profusely in the air and spread out laterally, form- 

 ing a dense network. They are of special importance in support- 

 ing the numerous branches, as in most cases the basal part of the 

 primary trunk has an early death. The roots themselves are very 

 stem-like in internal structure. The seerial roots or pneumato- 

 phores comprise an interesting feature of this tree. These are 

 erect or kneed branches of the roots, which project above the 

 mud, and are provided with stomata and lenticels, into which air 

 passes freely and is then carried by means of passages in the soft 

 spongy tissues to the underground roots. Like certain other 

 aquatic plants, the mangrove develops intercellular or internal 

 hairs in its air-passages. These hairs are of ecological signifi 

 cance in connection with the fluctuations in the air-supply, which 

 varies greatly, of course, with the rise and fall of the tides. 



The bark is at first smooth, reddish brown, becoming .35-. 50 

 inch thick, and gray faintly tinged with red. The surface is 

 irregularly fissured into low close ridges, these again are trans- 

 versely broken into thin appressed scales, giving a very character- 

 istic appearance to the old bark. The bark is red inside. It is 

 rich in tannin, and is used for tanning leather, and also in dye- 

 ing. The Florida Indians formerly used the copious bast for 



