THE PLANT ECOLOGY OF THE COAST BELT OF NATAL. 443 



quite fresli the maiig-roves give way to vlei types, which are 

 soon invaded by hygrophilous trees, e. g. Eugenia cor- 

 data, Voacanga dregei. Hibiscus tiliaceus (PI, XXV, 

 fig. 2). 



The interest of the mangrove type lies not so much in the 

 ground it occupies — for it is quite subordinate to other coast 

 bush in point of size — but in its being a southern outlier of 

 the great mangrove flora which lines the low-lying shores of 

 the tropics throughout the world. Northwards from Zululand 

 through Portuguese East Africa it becomes a very important 

 type, extending inland for many miles along the rivers. In 

 addition to the more hardy southern representatives, many 

 other species occur there — e. g. Ceriops candol liana, 

 Carapa moluccensis (Xylocarpus granatum), Lumnit- 

 zera racemosa, Soniieratia acida, Heritiera litto- 

 ral is, with the fern Acrostic hum aureum, as in Natal, a 

 common companion. 



9. BaRRINGTONIA C0NS0CI.=iS. 



This type is also much better developed in the tropics, and 

 has been dealt with by several ecologists, including Schimper^ 

 for India and Whitford^ for the Philippines. In Portuguese 

 East Africa, according to a note in the ' Flora of Tropical 

 Africa' (Oliver), Barringtonia racemosa "lines the 

 Rovuma River (Mosambique) for twenty miles (Kirk)." In 

 Natal Barringtonia consocies occur at the river mouths 

 above the lagoons and mud-flats in wet sandy soil, where the 

 Avater is not brackish . Barringtonia r a c e m o s a is dominant, 

 but other species which together form distinct associes 

 further inland are commonly associated Avith it, e. g. 

 Eugenia cor data and Voacanga dregei, with climbing 

 Iponieeas and many other subordinate hygrophilous scrub 

 species. 



Hibiscus tiliaceus is a very constant associate never 



1 Scliimper, A. F. N., ' Die Indo-maliiyische Strand-flora,' 1891. 



2 Wliitford, H. N., " The Vegetation of the Lamas Forest Reserve," 

 ' Philip. Journ. of Science,' i, 373, 1906. 



