The tree that bleeds ... metal?

Heavy metals like nickel and zinc are usually the last thing that plants want to grow next to in high concentrations.

But a specialised group, known as hyperaccumulators, have evolved to take up the normally toxic metals into their stems, leaves and even seeds.

Researchers have been studying Pycnandra acuminata in particular – a tree that grows on the island of New Caledonia in the south Pacific.

They think it may use the nickel to defend against insects.