GHARDAIA. 41 



THE MOUNTAINS ABOUT GHARDAIA. 



The vegetation of the low mountains and of the rocky valley walls is 

 extremely meager, mainly on account of the small amount or total absence 

 of soil. In certain places (for example, near Melika) the plants of the 

 hamada descend the rocky gulch nearly to the floor of the valley, and a 

 similar condition has already been noted at the heads of two of the larger 

 gulches. In such places we find species of grass and Haloxylon articulatum 

 mainly, but these species are not typical of this habitat. Only two forms 

 appear to occur on the walls of the valley or on the mountains, and nowhere 

 else. These are the "kabar," Capparis spinosa, and one or more crusta- 

 ceous lichens. (See figs. 2 2 and 23 .) The kabar is a large shrub, 1 to 2 meters 

 high, which bears persistent and fairly large leaves. The shrub is uneaten 

 by animals, owing to some disagreeable flavor,* but is provided with small 

 spines. The species is poorly represented, there being but few individuals, 

 and it does not exhibit exposure preference, but grows in crevices between 

 rocks, sometimes at the base of the walls, or wherever it can attain a foot- 

 hold. I have seen lichens on the flat and horizontal upper surfaces only of 

 a ridge of low mountains about 4 kilometers north of the valley of the 

 M'Zab; search failed to reveal any on the north surface of the mountains 

 or on any rocks vertically placed; their position would thus subject them 

 to the greatest temperature ranges and to the most intense aridity (fig. 26). 



THE VALLEY OF THE M'ZAB. 



The bottom lands, as already has been shown, are relatively favorable 

 for plant life; here the soil is the deepest and the water relations are the 

 best. Accordingly we should expect to find in the valley of the M'Zab 

 more plants than we have seen on the plain, and we will not be disappointed 

 in these expectations; but it is almost certain that in primitive times the 

 vegetation of the valley was even richer than at present. In fact we now 

 find in the unprotected places only such plants as are too small for fuel or 

 are not good for food, and the useful sorts are largely wanting. In other and 

 similar valleys, which have not been so much disturbed by man as the 

 M'Zab and where primitive conditions still largely obtain, there is a sur- 

 prising wealth of vegetation. Such conditions were seen between Ghardaia 

 and Ouargla and will be specially noted on another page. 



At present no trees occur naturally in the valley in the vicinity of Ghar- 

 daia or any of the sister cities. The French portion of Ghardaia contains 

 ornamental or shade trees, such as the ash, sycamore, and betoum. The 

 largest native shrubs are a species of Tamarix, growing by the oued, and 

 a few specimens of Zizyphus lotus, the latter confined to the side gulches 

 and numbering half a dozen specimens. Among the most generally dis- 



* We were informed by our Arab attendant that the kabar, particularly the fruit, 

 made such animals as ate it insane. The spicy flavor of the plant might otherwise be 

 distasteful to animals. 



