THE PLANT ECOLOGY OF THE COAST J^ELT OF NATAL. 445 



Plate XXV shows it developing after Phragmites which 

 follows after Avicennia near J3urban Bay. It is common 

 alone: all the streams. 



Other forest species invade it or grow up around its moist 

 margins, the seeds once more being brought by birds. The 

 hygrophilous bush thus serves as the base of colonisation for 

 the intervening ridges between the streams, as explained 

 later. The climbing plants, undershrubs and herbs occurring 

 in such hvgrophilous bush are the same as those found in the 

 coast scrub already described. 



11. PSAMMOPHILOUS BuSH. 



(PI. XXII, figs. 1 and 2; PI. XXIII, fig. 1.) 



This occurs on the fixed sand-dunes^ which line practically 

 the whole coast except at the river mouths, and vary in height 

 from 50 to 200 ft., and in width from a few yards to half a 

 mile. The dominant trees grow to a height of from 30 to 40 ft. 

 The early stages of the succession have again already been 

 dealt with. 



(a) The strand vegetation forms the initial stages. 



(b) The transitional marginal belt on the side next the sea 

 has also been described. 



(c) Following on this, there are several somewhat halophytic 

 varieties of scrub (PL XXII). Even though the majority of 

 the species are common to coast scrub generally, on the sand- 

 dunes they tend to show diiferences in growth-form and leaf- 

 succulence, which, taken in the aggregate, give the sand-dune 

 scrub a slightly different physiognomic appearance. The 

 following are characteristic species : Aloe thraskii (common 

 in open spaces), Chironia baccifera, Carissa grandi- 

 flora (14), Eugenia capensis, Cassine albanensis, 

 Celastrus procumbens, C. angular is, Canavalia bona- 

 riensis, Bauhinia tomentosa (399), Cynanchum natali- 

 tium, C. capense, C. schistoglossum, C. obtusif olium, 

 Turriea obtusif olia. Pas serin a filiformis, Osteo- 

 spermum moniliferum (55), Capparis zeyheri (214), 



