148 NEW ZEALAND PLANTS. 
extent, but on the whole exhibit their primitive characteristics 
(e.g., low tussock-grassland on the eastern portion of the Southern 
Alps); (8) imduced—z.e., where the action of man, intentional or 
otherwise, has brought imto being without cultivation a_ plant- 
association unknown, or extremely rare, in primitive New Zealand) ; 
(4) artificial—i.e., where man has purposely suppressed the original 
primitive association and substituted one of his own making (e.g., 
a Pinus radiata plantation or a field of wheat). The induced asso- 
ciations are a large class, and must be further subdivided into: 
(a) Indigenous induced —7.e., such imduced associations as consist 
principally or entirely of indigenous plants (e.g., Phormiwm swamp, 
the result of draining); (b) adventitious—z.e., where by the indirect 
action of man certain introduced species have constructed associations 
in which they are dominant (such associations may consist entirely of 
foreign species—e.g., gorse thicket in river-bed—or some indigenous 
species may also play a minor part). 
So far as the vegetation of New Zealand is concerned, the 
artificial plant-associations obviously can give no information regard- 
ing the evolution of the vegetation of the future ; on the other hand, 
the modified and induced associations have abundance of information 
to offer. There are, in fact, certain associations already settled firmly 
on the land which bid fair to be long-enduring features of the 
vegetation. Other associations are in process of evolution merely. 
Between the apparently stable associations and the first beginnings 
there are many transitions. 
Modified associations are extremely common features of the land- 
scape, but here only a few can be dealt with. Grazing-animals play 
a great part in modifying associations by reducing the. quantity—even 
to extinction—of the most palatable plants, and so altering the rela- 
tive abundance of the members of the particular association. In the 
early days of sheep-farming in Nelson the anise (Angelica montana) 
was extremely abundant in montane tussock-grassland, but for years 
it has been almost altogether absent ; indeed, except for the published 
writings of some of the early sheep-farmers, no one would have 
included it as a constituent of that association. Burning the tussock, 
if carried out year by year, will altogether eradicate the silver-tussock 
(Poa caespitosa) or the hard tussock (Festuca novae-zealandiae), but long 
before that happens bare ground suitable for plant-occupation will 
arise. In this way the catsear (Hypochoeris radicata), various grasses, 
