Armies of plant collectors travelled far and wide, gathering specimens that would beautify our gardens, such as dahlias, rhododendrons and chrysanthemums.

There are countless others that we now take for granted in an English country garden.

However, there are species that were introduced which have not been just ornamental but domineering.

Many have escaped to the wild, where they wreak havoc on an environment where they have no natural checks, such as grazing, insect damage or disease.

One particularly brutal invader is the Japanese Knotweed.

This was introduced as an ornamental plant by the Victorians but quickly ran riot in the English countryside and is now distributed throughout the British Isles and much of Northern Europe.

The leaves from the weed decompose very slowly, preventing seeds from other plants germinating.

The weed spreads very quickly from its rhizome root and thrives on disturbance.

Leaving even a small piece of root behind when clearing the weed will result in a new colony within weeks.

Now it seems that there might be a solution to the Knotweed problem.

Researchers have found that in its native Japan, Knotweed is not invasive since it has many insects and fungi that feed on it and other native plants that are able to compete with it.

Of all the species that feed on Knotweed, two were found to be species-specific and did not feed on any other plant, even those closely related.

Permission is now being sought to introduce these natural predators, a nymph and a leaf spot fungus into the United Kingdom.

While they will not eradicate Knotweed, they should help to arrest the spread of the plant.

This is welcome news for many of our countryside areas.

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