132 NEW ZEALAND PLANTS. 



Right at the north-east corner of Chatham Island is an old orchard 

 planted before the middle of the last century. At the time of my 

 visit, some years ago, I was astonished to learn that blights of all 

 kinds were quite unknown there, the extreme isolation of the orchard 

 having proved its salvation. And so, too, it was with New Zealand 

 orchards in the early days, before the coming of the microscopic weeds. 

 Many of the ills which afflict humanity are due to the presence 

 of extremely minute introduced plants known as bacteria, the 

 " microbes " of the journalist, and so various diseases now common 

 in New Zealand w r ere absolutely unknown to the Maori. 



From the plant-geographical standpoint, of particular interest 

 are any facts bearing on the struggle between the introduced and 

 indigenous species. The primary point to insist on is that so long 

 as the surface of the soil is left intact that is, if the primitive plant- 

 covering be quite undisturbed it is very hard indeed for the world's 

 selected weeds even those best equipped for aggression to gain 

 a foothold, and it is almost impossible for them to spread. On the 

 Snowcup Range, in Canterbury, there is a clear line of demarcation 

 between the meadows which are virgin and those where sheep are 

 pastured and burning is periodical. On the latter are introduced 

 plants in abundance, side by side with tussock-grasses, gentians, and 

 Spaniards ; but on the former there are merely the celmisias, butter- 

 cups, groundsels, and other mountain plants, the foreign invaders 

 being altogether absent. And yet the native dandelion, which is 

 closely related to the introduced species, is in abundance in many 

 places, and the violent westerly winds must be charged at times with 

 the seeds of certain weeds. 



Ruapehu, the upper portions of Egmont, and the mountains of 

 Stewart Island and elsewhere, especially on the west of the South 

 Island, are weedless. So, too, are the virgin forests. Disturb the 

 ground, however, and at once a seed-bed is ready, and the foreigners 

 pour in. Burning makes more space, and they spread and 

 increase, the native plants decreasing in proportion, and going to 

 the wall. Grazing animals assist in the destruction. The native 

 plants having come into being in the absence of such animals, 

 the moa excepted, are little protected against their attacks. At the 

 same time, the special equipment of the more aggressive introduced 

 species of plants makes these formidable. Many are annuals a great 

 advantage for rapid dispersal whereas almost all the indigenous species 



