发现无限37

Today, time and time again,we're hearing stories of species on the move.

Climate change and the great flow of human traffic around the globe means

that species once isolated, are now springing up in the most unexpected places.

And this mixing up of the world's species is starting to have significant consequences.

More than 40% of Britain's wild plants are exotic species,

introduced by us humans over the last thousand years.

That's sumac,not native.

Not native.

That's not native,that's not native.What's that?

That's Sycamore, that's not native.Yeah.

I've come to London's urban jungle with museum botanist Mark Spencer.

We're on the hunt for a new generation of exotic plants

that are about to change the face of the British landscape.

This here is the Loquat tree which is thought native to this country.

It's actually a plant from East Asia, China, Japan.

It's been grown in that part of the world for centuries.

And this plant itself has actually really just been grown as an ornamental

in this country for about 200 years,

and never produced fruit because for many years our climate just wasn't warm enough.

So what's different, what's going on now,then?

It's just beginning to be able to,really,in the last ten years or

so produce a lot of fruit. So for example in 2003, the really hot summer we had,

I saw trees in people's gardens in London with hundreds and hundreds of fruit.