198 EEPORT— 1891. 



and especially the annuals of cultivated grounds, are being in- 

 troduced into and disseminated throughout New Zealand, is a, 

 matter of much surprise to all observers, and not only to pro- 

 fessed naturalists. It is a point of very great significance in 

 reference to all inquiries relating to their superior powers of 

 propagating and establishing themselves, which the plants a& 

 well as animals of some countries display, as contrasted with 

 those of others ; and when, as in the case of New Zealand, the 

 result is the actual displacement and possible extinction of a 

 portion of the native flora by the introduced, the facts may 

 well arouse the interest of the most listless colonist. 

 I can here do no more than again call attention to the fact 

 that now is the time for certifying the dates of the introduction 

 of many plants which, though unknown in the Islands a quarter 

 of a century ago, are already actually driving the native plants- 

 out of the country, and will, before long, take their places, 

 and be regarded as the commonest native weeds of New Zea- 

 land." 



Since these reniarks were penned, another quarter ot a 

 century has passed, and the state of things they predict has in 

 many parts of the colony been already fulfilled. 



An interesting feature in regard to the spread of these 

 weeds is that different species show a remarkable difference in 

 their aggressiveness. Out of a number of different- plants in- 

 troduced, say, from Great Britain, where the conditions have 

 been tolerably uniform for a considerable period of time, and 

 where the struggle for existence has been very keen, it is 

 singular that, on introduction to new conditions such as pre- 

 vail in these Islands, some should exhibit such superior powers 

 of adaptation to others. Thus, among a score or so of species 

 of British Composites introduced into the southern part of the 

 colony, none, with the single exception of the thistle (Carchms 

 lanceolatus) , has shown such an aggressive character as the cat's- 

 ear or so-called Cape weed {Hypocliceris radicata). This plant 

 has spread itself far and wide, but disappears wherever sheep 

 are grazed. The causes for its extensive and rapid spread have 

 never been worked out, but it will probably be found that a 

 number of favourable conditions have combined to bring this 

 about. Its seeds are produced numerously, and are widely 

 spread by means of their pappus; they germinate rapidly ; the 

 young plant grows erect among grass, &c., but as it increases in 

 size its leaves broaden and gradually flatten out among the 

 surrounding vegetation, and so smother its immediate neigh- 

 bours ; its powerful tap-root enables it to flourisli and grow 

 strong when plants of more superficial growth are suffering 

 from want of moisture ; while its hisj^id surface and abundant 

 latex appear to render it distasteful to most insects. Further, 

 it blooms for many months of the year, and its flowers are ap- 



