Thomson. — Plant-acclimatisation in New Zealand. 313 



rhomboid lamina, the tip of which is usually reflexed. 

 Numerous glands occupy the median portion of the lamina, 

 the largest of which is placed at the base, and projects with a 

 kind of double head towards the column. Eows of smaller 

 glands reach the tip of the lamina, and at the sides of the 

 larger ones are smaller stalked calli. Column rather shorter 

 .than the upper sepal, broadly winged. 



North Island : Vicinity of Kaitaia, Mongonui County, 

 B. H. Matthews ! 



This is a most interesting and unexpected addition to our 

 flora. Mr. Matthews's specimens agree in all respects with 

 the beautiful plate in Fitzgerald's " Australian Orchids." 



Art. XXXIV. — Plant-acclimatisation in New Zealand. 

 By George M. Thomson, F.L.S. 



[Read before the Otago Institute, 10th July, 1900] 



A European botanist landing at any one of the principal ports 

 of New Zealand would be at once struck with the distinc- 

 tively British facies of the vegetation. Perhaps this impres- 

 sion would be most vividly produced at Lyttelton and Christ- 

 church, and least of all at Dunedin, for here the comparatively 

 good state of preservation of the native bush in and about our 

 Town Belt, and the proximity of so much high uncultivated 

 land, have left more of the indigenous vegetation than is to 

 be seen in the neighbourhood of any other of our large towns. 

 The causes which have led to the displacement of so much of 

 the native flora as has disappeared, and to the naturalisation 

 ■of so many foreign species of plants, are numerous and in 

 many cases not easily traceable ; the facts themselves are 

 conspicuous enough, even though the explanations may not 

 be forthcoming. 



In bringing this subject before you I am not going to 

 attempt at all to catalogue our introduced plants. That, I 

 hope, will be done in the completest manner by Mr. Cheese- 

 man in the Flora which he has now in preparation. What 

 I desire to do is to suggest reasons for the great increase and 

 aggressive character of some forms, and also for the failure of 

 others to establish themselves under what seem at first sight 

 equally favourable conditions. Why, for instance, should 

 gorse and broom, cooksfoot grass and meadow poa (Poa pra- 

 tensis), establish themselves so strongly as to become serious 

 pests in many parts, while attempts to introduce many 



