Well, quite a lot in terms of horticulture.The Victorians introduced many plants. Many of them examples of fine garden plants such as camellias, magnolias, Himalayan poppies and primulas.
Others Victorian introductions have proved to be alien invaders. At some point they have escaped from domestic situations to take over swathes of the countryside.
The most infamous is Japanese Knotweed (Fallopia Japonica). It was originally introduced as an ornamental plant by the Victorians but it has now widely naturalized and occurs across the UK as well as Europe, USA, Canada and New Zealand.
This herbaceous perennial which grows at an alarming rate of up to 10cm per day in any type of soil. It can form dense clumps of up to 3m (10ft) in height.
Japanese Knotweed thrives on disturbance and spreads by natural means and by human activity. Very small fragments of rhizome (underground stems), as little as 0.7g - approximately the size of a fingernail - can produce fresh new plants.
But it is below ground that the biggest problems occur, as each stand creates a rhizome network that can extend to 3m in depth and 7m in all directions. This makes it a serious threat to construction where it can have devastating consequences damaging foundations, drains and other underground services. And it makes it impossible to dig out!
I noticed it most recently pushing up slabs in a driveway of a garden in Orkney. It has even made it to the Northern Isles!
Another Victorian introduction is this attractive unassuming plant with the rather complicated flower. Looks can be deceptive.
This is common Himalayan Balsam (Impatiens glandulifera). P has always had a soft spot for the it after seeing it growing in a garden in the Highlands of Scotland.
Before I knew any better P convinced me that we should plant it in our garden in Orkney. I should have done some research....
Not long after this the late Elaine Bullard wrote an article in the local paper regaling us with not to plant balsam in our garden as it is a menace. Horrified I rushed out and removed before it could seed or take over the border. Even with it's ability to colonise an area I don't suppose it could spread that quickly....or could it?
Another alien lover of the riverbank is the Giant Hogweed (Heracleum mantegazzianum).
You can see why the Victorians were taken by this plant with it's large architectural leaves. Unfortunately the sap can cause severe skin inflammations. The plant can grow up to 5 metres in size and form a dense thicket that shades out other plants.
When the vegetation dies back in the winter it can leave the banks bare of vegetation.These are then liable to erosion or to recolonisation by seeds of Giant Hogweed washed downstream onto the bare ground.
It grows in swathes along the banks of several rivers in Angus.
Rhododendron ponticum is the scourge of the west coast of Scotland. You can see why the Victorians loved it. The glossy green leaves act as a stunning backdrop for the showy pale purple flowers.
It was introduced in the late 18th Century. It became especially popular on country estates in Victorian times, providing ornamental value, as well as cover for game birds. However, during the succeeding years, it has spread and is now destroying native plants in many areas.
Ponticum can reproduce by seed or vegetatively. A mature plant can produce can produce millions of seeds. Its canopy shades out ground cover plants and tree seedlings.
Where conditions are favourable such as in the west coast of Scotland it takes over large tracts of land lowering its biodiversity.
There are now programmes to rid areas of this plant. With so many of these very successful species it is easier said than done. Herbicides and manual removal are the methods used.The area then has to be monitored to prevent any seeds from germinating.
In the drier east coast Ponticum is not such a problem. This bush is growing in one of our local woods and had not got much bigger in the seven years that we have been walking there.
Do not be deceived!
I was recently asked by a friend how to get rid of snowberry that was growing into an ever increasing thicket in her garden. Digging it out by hand or continually cutting it back and covering it with black plastic is the organic route. I didn't really want to suggest Roundup...I think whatever course of action she took it would be a long haul.
When you wander round your garden centre, have you ever wondered how many recent plant introductions will turn out to be the invasive species of tomorrow?