L'Arbre du Ténéré, known in English as the Tree of Ténéré, was a solitary acacia, of either Acacia raddiana or Acacia tortilis, that was once considered the most isolated tree on Earth — the only one within more than 200 kilometres (120 mi). It was a landmark on caravan routes through the Ténéré region of the Sahara in northeast Niger — so well known that, along with the Arbre Perdu or 'Lost Tree' to the north, it is the only tree to be shown on a map at a scale of 1:4,000,000. It was located near a 40-metre-deep well at approximately .
It was the last surviving tree of a group of trees that grew when the desert was less parched than it is today. The tree had stood alone for decades. During the winter of 1938–1939 a well was dug near the tree and it was found that the roots of the tree reached the water table 33–36 meters below the surface.
One must see the Tree to believe its existence. What is its secret? How can it still be living in spite of the multitudes of camels which trample at its sides. How at each azalai does not a lost camel eat its leaves and thorns? Why don't the numerous Touareg leading the salt caravans cut its branches to make fires to brew their tea? The only answer is that the tree is taboo and considered as such by the caravaniers. There is a kind of superstition, a tribal order which is always respected. Each year the azalai gather round the Tree before facing the crossing of the Ténéré. The Acacia has become a living lighthouse; it is the first or the last landmark for the azalai leaving Agadez for Bilma, or returning.
The tree was allegedly knocked down by a drunk truck driver in 1973. On November 8, 1973 the dead tree was relocated to the Niger National Museum in the capital Niamey. It has been replaced by a simple metal sculpture representing a tree.
This was not the tree's first encounter with a truck. In his book L'épopée du Ténéré, French ethnologist and explorer Henri Lhote described his two journeys to the Tree of Ténéré. His first visit was in 1934 on the occasion of the first automobile crossing between Djanet and Agadez. He describes the tree as "an Acacia with a degenerative trunk, sick or ill in aspect. Nevertheless, the tree has nice green leaves, and some yellow flowers". He visited it again twenty-five years later, on November 26, 1959 with the Berliet-Ténéré mission, but found that it had been badly damaged after a vehicle had collided with it:
Before, this tree was green and with flowers; now it is a colourless thorn tree and naked. I cannot recognise it — it had two very distinct trunks. Now there is only one, with a stump on the side, slashed, rather than cut a metre from the soil. What has happened to this unhappy tree? Simply, a lorry going to Bilma has struck it... but it has enough space to avoid it... the taboo, sacred tree, the one which no nomad here would have dared to have hurt with his hand... this tree has been the victim of a mechanic...