Displacement and Replacement. s 287 » 
3. Adventitious tree-associations. 
2 Were no grazing animals present and fires suppressed, it is highly probable 
% that some of the many introduced foreign trees would seize on the open lands, 
and pine, Zucalyptus, Acacia and deciduous forests become established. 
In the vicinity of clumps of Ouercus sessiliflora ‘), young plants arise in 
thousands, and, if not suppressed, ae form thickets. Acer EEIBERERUS yi is 
%; 
a 5 
= stillmore Elke, and its wind power 
Salix fragılis and S. babylonıca, planted“ in the first place on river-banks, 
now, thanks to the rooting-power of broken twigs &c. line the margins of 
N Eee innumerable. 
E- The Cälifornian Pinus radiata, in some places, dots the pumice-heath of 
the Volcanic Plateau and closed associations have arisen in one or two places’). 
Where gumlands-heath has been burnt, Zucalyptus globulus has become 
established in a few places. At Waitati, near Dunedin, the burning of some 
dense Leptospermum scoparium allowed the seeds from a neighbouring example 
of Eucalyptus numerosa to germinate and there is a close pure tree-association, 
the Zeptospermum being altogether suppressed. 
Albizzia lophantha is self-established in many parts of the Auckland districts. 
Acacia dealbata°) is established in a few places, and both on dunes and 
gumlands increases rapidly by means of suckers. 
. Adventitious water-associations. 
The sparsely ie waters of the lowlands are rapidly occupied by 
foreign water-plants. Radicula Nasturtium-aquaticum, introduced as a salad- 
plant, rapidly seized on flowing streams in which it attains an enormous length 
of stem and frequently covers the entire water surface. 2 
Ranunculus sceleratus is a most abundant plant of vo where it ee a 
‚a pure society. 
The Australiär Ottelia ovalifolia is on the increase in les, ponds and 2 
‚shallow streams in the North Auc . district. e 
| Vallisneria spiralis is confined to lake Ti near. Ani. City, 
' where it is very abundant in water 1.8 to 2.5 m deep. en, 
one plant placed in the lake in 1885. Not being suitable for bir Mo 
is not liable to spread beyond y lake which has Da > connection with. any “ 
other lakes or streams‘). 2 = 
1).80 far as I know, neither of ihese trees, © as yet, have ipred pontane« 
original plantation, except into neighb 
2) It spreads readily from en on low Tumneksteppe the 
