128 XEW ZEALAND PLANTS. 



which are conspicuous in the Auckland Province the pokeweed 

 (Phytolacca octandra), for instance are absent farther south. Alti- 

 tude also thins the ranks, and at 3,000 ft. elevation, or less, indigenous 

 and foreign species meet on equal terms. On the sheep pastures of 

 the Southern Alps the beautiful alpine plants are still in abundance. 

 A condition of fair stability has come about, and new plant societies 

 have been formed in which the foreign invaders just hold their 

 own. But change the condition of affairs by fencing a portion of 

 land from the sheep, and the indigenous plants will at once increase. 

 At 2,500 ft. on the mountains of southern Nelson, Canterbury, and 

 (Jtago the gorse (Ulex europaeus) does not spread far and wide, as in 

 the lowlands, nor does it assume any remarkable dimensions. 



Amongst the introduced plants the most notorious are those known 

 by the opprobious term of ' weed." We all must know, though at 

 the present time it is difficult to conceive such a state of affairs, that 

 before the advent of the white man, and even for some considerable 

 time afterwards, there were no weeds in New Zealand. Mr. T. W. 

 Adams tells me how his land on the Canterbury Plain was at first 

 weedless.* A little further thought, and it is plain that in any virgin 

 vegetation weeds must be unknown, for what is a weed but merely some 

 plant growing where it is not wanted ? The mere presence of man in 

 a new land, then, creates weeds. There is no occasion for a plant to 

 be in itself useless to man to constitute it a weed. The best of plants, 

 such as potatoes, if growing unbidden in a flower - garden may 

 become weeds for the time being. Even in a New Zealand taxad 

 forest all the trees not required for milling purposes are weeds, or a 

 forest occupying ground intended for grazing is a distinct weed 

 association. 



Such well-known weeds as the sorrels, docks, fat-hens, and thistles 

 would in the original primeval world each have its proper place in the 

 primitive plant association to which it might belong, and would be 

 present in no abnormal numbers. It was the changes brought about 

 by cultivation, fires, and the close grazing of domestic animals which 

 upset the balance of nature. Then those plants whose structure 

 and habits were most in harmony with the changed conditions would 

 become more numerous at the expense of the less well-equipped, and 

 as the conditions antagonistic to the plant association as a whole 



* Of course, there would be plenty of introduced plants, but be meant those 

 kinds which overrun the land, and so become a nuisance. 



