530 ALTERATION IN FLORA SINCE 



the most aggressive plant of all is Pteris aquilina, which is rapidly over- 

 running much of the land that has been cleared of bush, and which 

 permanently establishes itself before its roots are sufficiently decayed to 

 admit of ploughing. 



The most abundant and most wide-spread introduced weed is Hypo- 

 chceris radicata. 



Cheeseman writes as follows on the naturalised plants of the 

 Auckland district: 



387 species are catalogued. Of these 280 are natives of Europe, many 

 of them also ranging into temperate Asia and North America, and some 

 into North Africa. Ten species, not European, are from the eastern portion 

 of N. America, and four are from the western. Total, 294 species from the 

 north temperate zone. From Australia only 19; from Chili and the cool 

 portions of S. America 9; from the Cape of Good Hope 21. Total 49 

 species from the south temperate zone. Finally 53 species subtropical 

 and tropical. 



31 are trees or shrubs, and 356 herbaceous. Of this latter number, 

 176 are annual, 28 biennial, 152 perennial. The large proportion of 

 annual species is noteworthy, as in the indigenous flora nearly all the 

 herbaceous plants are of perennial growth. 



With the above facts before us, we are better able to enquire into the 

 general subject of the naturalisation of plants in New Zealand and to 

 attempt an answer to the question why the native vegetation should 

 apparently be unable to hold its own against the numerous intruders 

 streaming in on every side. In considering the subject, it appears to me 

 most important to bear in mind constantly that the conditions of plant- 

 life now prevailing in New Zealand are in great measure different to those 

 that existed when European voyagers first visited its shores. When Cook 

 landed here the whole country was covered with a dense native vegetation, 

 hardly interfered with by man. The cultivations of the Maoris were small 

 in areas, and as they rarely tilled the same plot of ground for many years 

 in succession, preferring to abandon it when the soil showed signs of 

 exhaustion and to make new clearings elsewhere, there is little chance of 

 the establishment of a race of indigenous weeds. In fact, it can be roundly 

 said that the New Zealand Flora contained no such class. At that time 

 there were no herbivorous animals of any kind, either wild or domesticated, 

 to graze upon the vegetation, or to interfere with it in any way. Thus no 

 check existed to the growth of many species which can now hardly live 

 in a district where our introduced cattle are abundant. And the repeated 

 burning off, year by year, of large tracts of open country, was then a 

 circumstance almost unknown. The Maori rarely wantonly destroyed the 

 vegetation, and if he used fire in making his new clearings, generally took 

 precautions that it should not spread further than was absolutely required. 

 It is hardly necessary to dwell longer on this point; for all must admit 

 that the advent of European settlers and the colonisation of the country have 

 brought into operation a set of conditions injurious to both the indigenous 

 fauna and flora. The chief of these conditions may be conveniently grouped 

 under three heads: first, the actual destruction of the vegetation by the 



