200 BOTANY 
undersides of the leaves, well shown in the great variety 
of olearias that flourish here. 
The Sand Dune vegetation is again of a xerophytic 
character. The poor water-holding capacity of the sand 
itself and the constant winds that sweep over 
these areas render this a necessity. Sand plants, 
however, particularly the pioneers of the society 
show special adaptations. To fix the shifting 
LD. oats PAD., HRS pho 
Sub-alpine Scrub, Stewart Island, (Olearia colensoi on right, manuka on left) 
sand they must either produce a dense mass 
of roots, or, as is more commonly the case, of under- 
ground stems that will bind the material of the dune 
together. The silvery sand-grass (Spinifex hirsutus) 
and the pingao (Scirpus frondosus) are two of the 
commonest sand-binders. The underground stems of the 
latter form an interlacing mass in the interior of the 
dune, while the stems of the former, produced originally 
on the surface, soon become buried with similar results. 
The low-growing habit of the sand plants, as seen in the 
