Where was the most isolated tree on Earth located?

The Ténéré Tree was a solitary acacia, the only one for over 400 km, located in northeast Niger. It was a landmark on caravan routes through the Sahara Desert, so well known that it and the Lost Tree to the north are the only trees to be shown on a map at a scale of 1:4,000,000. It was knocked down in 1973 by a drunk truck driver.