Here is a strange tree that will surely remind you of another specimen from the series, the Okavango baobab. Perhaps a “cousin” species? In any case, Lake Eyre—or more precisely, the endorheic basin of Lake Eyre— is located in Australia and covering 20% of its surface (equivalent to the combined area of France, Germany, and Italy) and somehow manages to be even stranger than the Okavango.

Let’s clarify one term: an endorheic basin is a geographical area where the tributaries and sub-tributaries of a lake or river flow towards an inland delta or a closed lake but don’t reach the ocean.

Like Australia’s exceptional, bizarre, and sometimes very dangerous wildlife, the Eyre river-tree (or rather, lake-tree) is almost extraterrestrial compared to the other rivers in the series. First, there’s its bush-like structure, with no mouth, and its semi-permanent watercourses that thin out through evaporation as they flow toward the bottom of the basin, only during years of heavy rain. Let’s not froget its extreme aridity and heat, which make this region—part of the Australian Outback—dangerous and inhospitable to human life. To top it all off, this odd tree can boast the oldest branch on the planet: the Finke River, at 400 million years old, which is ironically not even connected to the rest of the organism. When it does flow, a few days a year, it is absorbed by the Simpson Desert. Most of the monsoon rains from the northeast never reach the lake, located 1,000 kilometers to the south, that lies 16 meters below sea level.

Lake Eyre shares another feature with the Okavango and its system: salt lakes, large expanses of salt-rich land that are almost perfectly flat and only hold water for a few days each year. They are formed by the accumulation of salts carried by the water, but when the water evaporates, the salts remain and settle. This lake is, in a way, the heart of the tree, irrigated from all sides, and then returning the vital liquid to the sky through evaporation to feed the great global organism. And if this metaphor doesn't convince you, take a look at the photos showing the lake and its unique color.

Lake Eyre and its basin may have a big heart, but it is merely enough for the 60,000 humans who live within its boundaries. And for good reason: without water or irrigation channels to bring it in from elsewhere, life cannot thrive, except for the extensive livestock farming that drives the local economy. Some animals and plants, which evolution has sometimes been more generous to in terms of adaptive abilities, can cope perfectly well with this water shortage, but when the rivers come back to life, filled with rainwater, a celebration begins: birds and mammals converge on the lake's waters, while the shores turn green with joy.

On these shores, we find a tree, the Eucalyptus coolabah, or simply Coolabah. This tree is a member of the large Eucalyptus genus, some of whose species are huge and very leafy and are associated with Australia and Tasmania, where they originate. No wonder, when you consider that three-quarters of Australia's forests are made up of some of the 700 species that make up the genus. The coolabah is an ideal ambassador to represent the Australian hinterland, the Outback, which comes back to life when it rains along green veins, as this tree has evolved to be perfectly in tune with its environment. Its ochre or reddish wood is also reminiscent of the Outback soil, and for thousands of years it has been used by Aboriginal peoples to make spears, plates, utensils, and message sticks.

Eucalyptys Eyre, Eucalyptus Eyrensis