Harvesting metal from plants that suck it out of the ground

"Hyperaccumulator" plants grow in metal-rich soiland suck a huge amount of metal out of the ground.

If you cut open the leaf of a hyperaccumulator plant, you get sap that's blue-green, because it's fully 25% nickel. That's an astonishingly high concentration; it's higher than the ore that goes into a nickel smelter. — Read the rest