The black and grey rats have driven the native rat into the recesses of the forest.

A score of weeds have come, mixed with badly-screened grass-seed, or in any of a hundred other ways.

The Scotch thistle seemed likely at one stage to usurp the whole grass country.

Acts of Parliament failed to keep it down.

Nature, more effectual, causes it to die down after running riot for a few years.
The watercress, too, threatened at one time to choke half the streams.
The sweetbriar, taking kindly to both soil and climate, not only grows tall enough to arch over the head of a man on horseback, but covers whole hillsides, to the ruin of pasture.