136 
POPULAR SCIENCE REVIEW. 
arvense, which covered the new-formed banks, for miles and 
miles, with the most lovely green forest of miniature pines. In 
the following year comparatively few of these were to be seen, 
and coltsfoot, dandelions, and other biennials, especially Um- 
belliferse, with a great number of annuals, presented them- 
selves. For many successive years I had no opportunity of 
watching the struggle for life on these banks, but when I last 
saw them they were clothed with perennial grasses, docks, 
plantains, and other perennial rooted plants. 
The destruction of native vegetations by introduced is a sub- 
ject that has only lately attracted much attention, but it has 
already assumed an aspect that has startled the most careless 
observer. Some thirty years ago the fecundity of the horse and 
European cardoon in the Argentine provinces of South America, 
so graphically described by Sir Edmund Head, drew the atten- 
tion of naturalists to the fact, that animals and plants did not 
necessarily thrive best where found in an indigenous condition ; 
and the spread of the common Dutch clover. Trifolium repens , 
in North America, where it follows the footsteps of man through 
the pathless forests, has long afforded an equally remarkable 
instance of vegetable colonisation. Still more recently, in 
South Africa, Australia, and Tasmania, the Scotch thistle, briar 
rose, Xanthium, plantains, docks, &c., have all become noxious 
weeds ; and this leads me to the last and most curious point to 
which I shall allude in this article, viz., that the same annuals 
and other weeds, that are held so well in check by the indi- 
genous perennial plants of our country, when transplanted to 
others, show themselves superior to the perennial vegetation of 
the latter. Of this New Zealand famishes the most conspicuous 
example, — it was first visited scarcely more than 100 years ago, 
and it is not yet fifty since the missionaries first settled in it, and 
scarce thirty since it received its earliest colonists. The Islands 
contain about 1,000 species of flowering plants, amongst which no 
fewer than 180 European weeds have been recorded as intruding 
themselves, and having become thoroughly naturalised ; and 
probably double that number will yet be found, as they have 
never been systematically collected; but the most curious part 
of the history is this, that whereas of indigenous New Zealand 
plants scarcely any are annual, no less than half the naturalised 
European ones are annual. 
Of the effect of these introduced European plants in destroying 
the 'native vegetation, I have given examples in an article 
that appeared in the Natural History Review (January, 1864), 
from which I quote the following : — 
In Australia and New Zealand, the noisy train of English 
emigration is not more surely doing its work, than the stealthy 
tide of English weeds, which are creeping over the surface of 
