the final episode deals with plants that live in hostile environments. Attenborough visits Ellesmere Island, north of the Arctic Circle, to demonstrate that even in a place that is unconducive to life, it can be found. Algae and lichens grow in or on rock, and during summer, when the ice melts, flowers are much more apparent. However, they must remain close to the ground to stay out of the chilling wind. In the Tasmanian mountains, plants conserve heat by growing into 'cushions' that act as solar panels, with as many as a million individual shoots grouped together as one. Others, such as the lobelia in Mount Kenya, have a 'fur coat' of dense hairs on their leaves. The saguaro cactus in the Sonoran Desert flourishes because of its ability to retain vast amounts of water, which can't be lost through leaves because it has none. Many desert dwellers benefit from an accelerated life cycle, blooming rapidly within weeks after rainfall. Conversely, Mount Roraima is one of the wettest places on Earth. It is a huge sandstone plateau with high waterfalls and nutrients are continuously washed away, so plants have to adapt their diet if they are to survive. A bladderwort is shown invading a bromeliad. Inhabitants of lakes have other problems to contend with: those that dominate the surface will proliferate, and the Amazon water lily provides an apt illustration. Attenborough ends the series with an entreaty for the conservation of plant species.

A visit to the Amazon jungle - the world's largest rainforest and home to the widest variety of plants and animals on Earth. he diversity of life in the jungle is so great that in just two square miles scientists have counted 3,000 varieties of ants, 530 types of birds and 11 species of monkey. But despite the huge range of life that flourishes here, survival is never easy.

Earth's surface is covered in weird and wonderful patterns. The Australian outback is covered in pale spots, the work of wombats; a clearing in the endless green canopy of the Congo rainforest has been created by an incredible elephant gathering; and the twists and turns of the Amazon make a home for rehabilitated manatees. This is our home, as we've never seen it before.

Francisco de Orellana failed to find El Dorado, but discovered the Amazon. Early in 1541, a rumor swept Quito that beyond the mountains, there lay a land richer than Mexico, or even Peru - a land of gold. The ruler of this land was so rich that he covered himself with gold dust every day and washed it off every evening. He was "the golden man", El Dorado. They had tree goals: to find La Canela, the land of cinnamon: to assess new lands for colonization; and to find El Dorado. On march 1541, They marched eastwards with more that 200 Spanish troops and thousands of native servants.

A look at the unique habitat which is formed every year when the Amazon floods an area of forest the size of England. It creates a world that is home to turtles, caiman and giant otters, and where fish fly through the air and dolphins hunt amongst the tree tops.

Michael crosses Iran towards the Caspian Sea. He meets nomads who tell of Alexander's tryst with an Amazon queen, and the living descendants of Alexander's Persian enemies, who have their own tales of `Alexander the Accursed'.