Image copied from linguistics.ucla.edu
Image from Wikimedia Commons is by Michel Mazeau
For decades it held the distinction of the remotest tree in on the Earth. Visible from a large distance in vast Saharan plain it used to act as a landmark in the desert for the traders/travellers travelling through the area.
Image from Wikimedia Commons is by Holger Reineccius
Later at the very spot where the tree stood, some unknown artist created a metal tree from pipes, used tyres and empty drum, as a monument to the dead tree. Thus the location still acts as a landmark.
Image from Panoramio is by naglwitz
Image from Panoramio is by inivag
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Info Source: Wikipedia
More details and photos at L'Arbre du Ténéré and
http://www.agadez-niger.com (in French). (English Translation)