76 The Vegetation of the Sea-coast. 
'd. Fixed-dıme. 
This, the climax of constructive dune-building, frequently lies far back 
from the sea, and is of considerable age and perhaps denotes a rising coast. 
In places where the wind strikes obliquely, or is not frequent, fixed-dune 
may lie just behind the foredune. E 
The sand is covered by a much more cohesive humus-containing lag 
of blackish sand, than is that of unstable dune. It is sometimes as much as 
30 cm in depth, formed from the decay of many generations of plants. 
At the present time, the vegetation is much modified. It consists of 
grassland or a heath of Cassinza, Leptospermum or Pteridium esculentum. No 
longer primitive, the grassland contains many introduced grasses and Zegumznosae, ; 
together with forms of Danthonia pilosa and D. semiannularis. 
 localities. 
are abundant and there are many silvery patches of Raoulia australis and 
R. Beawerdii; tussocks of Poa caespitosa also are plentiful. Pimelea Lyalliü 
replaces P. arenaria, and other plants not found on dunes further N. are 
Geranium sessält florum ar. ee ERTENEEIENR congesta and Gnaphalium 
trinerve. 
e. Se and sand-plains. 
- An advancing. dune-ridge leaves, in its wake, flat sandy ground which 
may continue to be further hollowed out by eh until moisture rising 
from the water-table damps the surface-sand and stops further sand-movement. 
stage of stabihäiy: and. a succession of associations s Cuinaing in a climax-asso- 
‚ciation. ee er ag er 
< In the Eastern, R hine-Cook, E t-Wanganu: i and, at times, the North 
Auckland distriets the first-comer on the damp sand i is Gunnera arenaria whic 
forms circular mats 8Socm — 2m in diam., the small, thick, pale-green 01 
brownish leaves flattened. to the ground. Barbie cernuus, Ranunculus acanlı : 
Epilobium Billardieranum, 2 nerteroides, Crantzia lineata and especially Car: 
 umila are characteristic. Lodelia anceps, Limosella aquatica and Myriop 
Votschii are abundant in the N. and C. Should there be no invasion of ‚an 
Sigg, ee ee next occupy this. non-t halophytic allge, 
