On the upland eastern plateaux, and especially in the districts frequented by the Mememsha and Haracta tribes, the prevailing plant is theguethaf (atriplex halimus), which supplies an excellent fodder for the camel, A common species on the plateaux is also the dis (ampelodesmus tenax), which resembles the halfa grass, and which is used by the Arabs for thatching their huts and for making cordage, The terfas, or white truffle (tuber niveum), is widely diffused throughout the Oran uplands and in the Hodna districts, Together with the parmelia esculenta, a species of edible lichen known as "munna," it serves as a staple of food amongst the natives.
Nor is the Sahara itself so destitute of vegetation as is commonly supposed. Besides the palms and undergrowth of the oases, such as fruit-trees, herbs, and
vegetables, hundreds of plants grow on the clayey, rocky, sandy, and marshy tracts of the desert. But there is an absence of European species, and the chief affinities are with the flora of Egypt, Palestine, Arabia, and Southern Persia. Altogether the Sabarian flora comprises 560 species, of which about a hundred are indigenous. But the number might be easily increased, and several useful varieties have already been introduced by Europeans in districts where water is available. The sands themselves might be clothed with vegetation, and several species growing spontaneously on the dunes, help to. bind the shifting masses and convert them into solid hills. Amongst them is the drin (arthratherum pungens), the grain of which in times of scarcity serves as a substitute for barley.
