Some very old great cypress trees have survived in Tassili on wash bed between rock masses and towers.These relic trees can no longer reproduce due to insufficient rainfall. These endemic trees (Cypressus Dupreziana) are called "Tarout" in Tamahaq dialect. The cypress trees which survived thanks to its resistance in this arid region is a big interest to scientists. All knows trees has a painted number on his trunk. Two examples there pictured in Tamrit and Rayeye localities.