— 207 — 



B. The Halophyte Vegetation. 

 I. The muddy soil vegetation. 



1. The Mangrove formation. 

 (Gfr. B0rgesen, 1898, p. 27; 1900, p. 25.) 



In the Danish West Indies this consists of the three species, 

 Rhizophora mangle L., Avicennia nitida Jacq. ') and Laguncularia 

 racemosa G. each species of which forms belt-hke associations, in 

 such a way that the Bhizophora-assoc'iaiion grows outermost, at 

 the lowest level, the Avicetinia-Rssociaiion in the centre on some- 

 what higher ground, and the Laguncularia-Rssoc'iation innermost 

 on the highest and driest ground. 



As already mentioned in my earlier paper, the mangrove 

 formation is commonly present on the coasts of the islands where 

 it is sheltered. It further often, but far from always, fringes the 

 salt-ponds, lakes with shallow more or less brackish and often 

 stinking water, which rarely or never is renewed, as the sea only 

 exceptionally is capable of washing over the low sand-dunes which 

 shut off the ponds from the sea. 



The soil, on which the mangrove vegetation is growing, is 

 commonly fine, soft mud and clay, sometimes mixed more or less 

 with sand, but mangroves growing on gravel are also to be found; 

 just as Rhizophora is to be found growing on rocky coast, where 

 it attaches itself to the rock in cracks and crevices, as Jobs. 

 Schmidt (1903, p. 4) mentions may also be the case in Siam. 



In the Danish West Indies the mangrove grows either in the 

 sea itself in shallow water at not more than 1 — IV2 metres, or in 

 the immediate proximity of the level of the sea where the bottom 

 is often covered by only a few inches of water; but long stretches 

 of mangroves can also be seen growing so high that for long 

 periods they are laid dry and in any case only occasionally washed 

 over, when the sea is very high, 



Schmidt has (1. c. p. 4 — 5) given the following definition of 

 the mangrove in Siam. "The mangrove is the formation of tree- 

 like evergreen plants which live on the sea-coasts, and at the 

 mouths of the rivers, and which normally are only found where 

 the soil is either constantly washed over, or at all events regularly 



^) Eggers (1879 p. 84) also locates Avicennia tomentosa Jacq. to St. Croix. 



