Welwitschia mirabilis. This unique plant consists of a woody stem and two large leaves. It is evergreen and the leaves grow continuously along the ground, often becoming frayed. W. mirabilis is endemic to the Namib desert, the most arid environment on Earth. It survives this environment partly because of its roots, which can grow to depths of 30 metres. The oldest living plant is 1500 years old. The largest leaf found is 6 metres long and 2 metres wide. Photographed in the Namib desert.