T. Kirk. — Displacement of Species in New Zealand. 21 



nately, I had not time to visit it. These three species were 

 ahke extending their area mainly in the direction of the pre- 

 vaihug winds, and would, I am convinced, be able practically 

 to replace the indigenous vegetation over the entire area if 

 not interfered with by man. This instance of replacement is 

 replete with interest, as it is almost the only case in which there 

 is clear evidence of the seeds of phanerogamic plants having 

 been carried by aerial currents over a distance of from 1,200 

 to 1,400 miles and becoming established in a new country. 



Displacement and Increase. 



The blue-gum (Eucalyptus globulus,'''- Lab.) in some locali- 

 ties shows itself able to compete with the indigenous vegetation 

 under special circumstances. Seedlings germinating amongst 

 manuka 4ft. or 5ft. in height will speedily overtop it. In 

 several localities self-sown plants are found by thousands, and, 

 as a second generation of naturalised plants is already to be 

 found, there can be no doubt that if not interfered with it 

 would entirely alter the aspect of large portions of the colony. 

 E. piperita (Sm.) and E. rostrate (Schl.) appear to have the 

 same power of adapting themselves to new situatioiis, although 

 perhaps not to an equal extent. 



The brush-wattle {Albizzia lophantJia, Benth.), a native of 

 Western Australia, is able to destroy the strongest vegetation 

 in open manuka country, as may be seen in numerous locali- 

 ties ; while the tan-wattle {Acacia decnrrens, Willd.) and the 

 silver- wattle {A. dealbata, Link.), although much slower, are 

 equally effective in the northern districts. Another Australian 

 plant, Hakea acicularis]- (Sm.), according to Mr. Cheeseman, 

 " has established itself over several miles of open manuka 

 country at the foot of the Waitakerei Ranges, and is increas- 

 ing fast." Gobbet's locust-tree {Bobmia pseudacacia, L.) forms 

 large groves in the Waikato and other localities ; its lofty 

 stature and numerous suckers effectually prevent the growth 

 of other vegetation. The well-known furze (Ulex europcBus, 

 L.), by its dense habit, has killed tauhinu (Pomaderris phy- 

 licifolia, Lodd.), manuka, kc, over large areas, and is continu- 

 ally extending, while its near relative, the broom (Gytisus 

 scoparias, Link.), is no less troublesome. The injury to 

 pasturage caused by the sweetbriar (Rosa rubicjinosa, L.) is 

 unhappily too well known to need special mention ; but few 

 are equally famihar with its power of overcoming manuka 

 and other shrubs of similar habit. The dog-rose {B. canina, 

 L.) exerts the same influence to a less extent in several dis- 

 tricts of the South Island ; while various forms of the European 



' Ti-ans. N.Z. Inst., vol. xvi. (ISS^;, p. 383. 

 t Trans. N.Z. Inst., vol. xv. (1882), p. 291. 



