They contain stunted timber trees, palms, mangroves and other tropical and sub-tropical plants and have an almost impenetrable undergrowth.
The coastlands of Natal and Portuguese East Africa, the vegetation is abundant, and mangroves, palms, baobab and bombax trees flourish.
From the sea the only indication of a river mouth is a break in the dark green mangroves which here universally fringe the coast.
Studer (Crustacea of the Gazelle, 1882) records Balanus amphitrite (Darwin?) from roots and stems of mangroves in the Congo, where, he says, " it follows the mangroves as far as their vegetation extends along the stream, to six sea-miles from the mouth."
The west coast throughout its whole length is covered to a depth of some miles with mangrove swamps, with only a few isolated stretches of sandy beach, the dim foliage of the mangroves and the hideous mud flats presenting a depressing spectacle.
On the east coast the force of the north-east monsoon, which beats upon the shores of the China Sea annually from November to February, has kept the land for the most part free from mangroves, and the sands, broken here and there by rocky headlands thickly wooded, and fringed by casuarina trees, stretch for miles without interruption.
The coast region is characterized by mangroves, Pandanus, rattans, and similar palms with long flexible stems, and the middle region by the great rice-fields, the coco-nut and areca palms, and the usual tropical plants of culture.
In places the sands are fringed by long lines of Casuarina trees; in others, and more especially in the neighbourhood of some of the river mouths, there are deep banks of black mud covered with mangroves; in others the coast presents to the sea bold headlands, cliffs, mostly of a reddish hue, sparsely clad with greenery, or rolling hills covered by a growth of rank grass.
The flora includes mangroves, Rubiaceae, Sapotaceae and other forms requiring more than pure coralline material for their growth.
Beyond the delta firm ground takes the place of mud and the mangroves disappear.
The seashore and the river banks are lined with mangroves, but the most important tree of the coast belt is the oilpalm.
(or as far as Sunday Island, the limit of the sea tide in the dry season) dense lines of mangroves 40, 50, or 60 ft.