Flora

Due to the scarcity of water, the Sahara is almost devoid of flora. From the Mediterranean vegetation which used to cover the Sahara mountains before it becomes a desert, there is only the oleander and cypress of Tassili near gueltas.
The plants have adapted to the environment to reduce evaporation and increase water absorption: very small leaves, very long roots that can dive in the most humid layers of soil (acacias, tamarisks), water accumulation in tissues and leaves covered with wax (succulent), losing roots and getting carried away to absorb atmospheric moisture (roses of Jericho), sucking lymph of roots of other plants (cystanche), losing its leaves in case of aridity and growing them back in the wet season (zilla), inedible leaves (Apple of Sodom), ...
There are some isolated bushes (tamarisks, acacias) in the wadi beds. The rare precipitations can give life to a temporary meager meadow, the acheb, sought by nomads.
The date palm, introduced by the Arabs, is essential to the existence of Man in the oases: dates are a very energetic food, its trunks are used to make beams, its foliage is used to make baskets, ropes, mats and covers for huts... it protects fruit trees from sun, and these trees in turn protect vegetable crops.