Extras
Sir David Attenborough reveals how humans help plants, many of which face extinction.
Watch vines and balsa trees fight out who will get to the top of the canopy.
Sir David Attenborough reveals the surprising effects of the seasons on plant life.
Marksmen use paintballs filled with herbicide shot from a helicopter to stop Miconia.
Tristerix seeds travel in bird droppings to invade the bodies of giant cactus.
The baobab stores thousands of gallons of water in its spongy wood.
The saguaro features a pleated surface which allows it to expand.
Fungi is able to link a whole group of trees through their root systems.