FLORA OF I'OKTUGUESK EAST AFRICA. 297 



Sterctiliaceae : Hcriticni liftoralis. 

 Verbenaceae : Aiicciiiiia ofpciiialis. 



The fern Acrosfichuiii aurciDii is an occasional companion to 

 these, while on slightly higher but still saline localities 

 Tliespesia populnea, Hibiscus iiliaccus and several reeds and 

 grasses appear, but on the tidal flats the mud is bare, even 

 Cyperaces. Gramineas and Salsolacea; being" very sparingly 

 represented. 



In the southern part of the Province several of the tropical 

 mangroves are absent ; the more hardy ones extend south to 

 Natal and Transkei but also occur throughout the tropical 

 shores, and most of the species are not confined to African 

 shores. 



The export of mangro\e bark for tanning purposes has been 

 a source of considerable income in the past, but indiscriminate 

 shipping of the bark of the several species has affected the 

 reputation of local bark. 



Owing to the rapid exhaustion of the better kinds Govern- 

 ment has now temporarily prohibited the export of mangrove 

 bark, but encourages the plantation of those kinds likely to be 

 of use. Ai'iccnnia, which has little value, and no bark value, 

 has practically taken possession of all such localities outside 

 the tropic, and unless controlled or destroyed is likely to main- 

 tain that dominance. 



The mangroves have a considerable value in fixing tidal mud 

 and aiding the settlement of further mud until the altitude is 

 sufficient to allow grasses to grow, after which the gradual 

 rising of the land continues. In this way probably manv of the 

 mud fiats near the Zambesi have risen out of the sea or river, 

 and are now above the mangrove level, though still swampv 

 during rains. The mangroves, however, extend inland along 

 the rivers for manv miles. 



II. Littoral Regiox. 



This comprises two classes of localities, and also extends the 

 whole length of the Province. 



In the south it is mostly in the nature of sand-dunes, the 

 vegetation of which has already been referred to as l)eing an 

 overlap from the south, and many such Gape sand-dune species 

 extend to the Zambesi. 



Bevond the Limpopo, however, fresh species appear, 

 especially Casuarina, which, standing erect and rigid on bare 

 sand-dunes, forms a striking object along the coast, recog- 

 nisable from a long distance out at sea. 



Sitnana uiariiima, Sophora foinciitosa, Diospyros sp., 

 Gucttarda spcciosa, etc., appear further north, and the exotic 

 cocoa-nut and mango form features near the lower rivers. 



The second class of locality belonging to this region in- 

 cludes such coast localities as are just above tide mark but are 

 flat swamps, or extending gradually toward dry land. Bar- 

 ringtonia vaccniosa. Hibiscus tiliaccus, Pliccnix rccliiiata, 

 Eugenia curdaia, J'oacanga Tliouarsii. and several species of 



