. Shrub Associations. 217 
hish mountains, form either a belt above the forest-line or make thickets, large 
or small, on river-beds, in gullies, in hollows and even on mountain-slopes. 
The general ecological conditions that determine the presence of the form- 
ation are, — altitude, (which decreases from N. to S. or according to edaphic 
xerophily); violent wind, (but less than herb and, grass formations can tolerate); 
a heavy winter snow-fall, (but not the maximum), and frequent rain at all sea- 
sons. This last factor leads to the presence of a xerophytic soil rich in peat 
or raw humus. But, in the dry mountain areas, scrubs likewise occur, some 
of which are strongly bound up with edaphic conditions, as in the case of the 
serpentine Mineral Belt and the Sewecio Monroi scrubs of the North-eastern 
botanical district. 
The species number about 108 which belong to 26 families and 45 genera. 
Sixty eight species are common to subalpine-scrub of both the North and South 
Islands, 7 species are peculiar to the former and 31 to the latter island. Stewart 
Island contains 42 of the species in the above total estimate, but ı0 do not 
occur in the formation while a number of the remaining play a very minor 
part‘).“ By far the greater part of the really important members of the sub- 
alpine-scrub, as. a whole, consists of Taraceae, Epacridaceae, Rubiaceae and 
shrubby Compositae. Nothofagus cliffortioides, N. Menziesii, Gaya ER and 
Suttonia divaricata are also important members in many localities. 
Coming now to the growth-forms, there are go shrubs or stunted trees, 
ı liane, 5 herbs or subshrubs, 4 grass-like plants and 8 ferns. Regarding the 
shrubs &c. the most important growth-forms are: — the shrub-composite 24; the 
Dracophyllum 6; the divaricating ı3 and the more or less cushion-like 5. Many of 
. the remainder are of much closer growth, than normal, with their branches 
gnarled and crowded together. With regard to leaves, 46 species have them = 
small and coriaceous, 26 medium and coriaceous, 6 rather long and neede- 
like, 3 cypress-like, 3 large and coriaceous, 4 Have eg Br and 23 ‚have Sr 
ense tomentum on the undersurface. Bee 
The subalpine-scrub associations differ from c one another in lensity, floristic 
composition and in different localities, and di Issimilar serubs may 
 0CCUpy contiguous® ‚According as shrub- composite, < : xad, 
 Gaya Lyalli, Piyliocladus alpinus, stunted Nothofagus, Dracophylium or var | 
deating-shrub dominate, so is there a different and distinct facies. In many 
Parts of the Southern Alps Phyllocladus and Gaya lend a most distinet ae 
‚ance to adjacent patches of scrub. er 
A typical subalpine scrub of a wei climate consists: of a unter. of r 
. Or wiry-stemmed shrubs which grow into one another while the main branches 
of many are parallel to the slope and project downwards. > The In may 
= Be from .n and the roof 223, even. The rn be so 
a S 1) In adäition Olearia divaricate and a Dracpit Ä 
Stewart Island only | | 
