22 BOTANICAL FEATURES OF THE ALGERIAN SAHARA. 



especially Artemisia herba-alba, with Tamarix and a few specimens of 

 Pistacia along the oueds or where water conditions are most favorable. 

 Between the belt of alfa last mentioned and El Masserane, a bordj, there 

 is a broad plain surrounded by low mountains, which are really the north- 

 ern extension of the broad Saharan Atlas, where salt-bushes occur in a 

 formation several kilometers, possibly 24, across. Here in the summer the 

 nomads, coming up out of the desert, find grazing for their flocks, and even 

 in October we saw countless numbers of sheep and goats, and hundreds of 

 camels, browsing the shrubs. 



At El Masserane are specimens of large Tamarix, really the size of small 

 trees, growing near the bordj ; and to the south of the bordj we passed the 

 first dunes encountered on the plateau. These are part of a series of dunes 

 which were seen to extend to the horizon to the northeast, as we approached 

 El Masserane, and which, we were informed, reached as far as Bou Saada, 

 nearly 90 kilometers distant. The dune flora was quite different from that 

 of the surrounding plain, owing to the total absence of salt plants, and to 

 the presence, among other species, of a Tamarix and a large grass, the 

 "drinn" (Aristida pungens), which was subsequently frequently seen. 



Soon after passing the dunes the way lay through a country with low 

 mountains, almost bare of vegetation, where scattering oaks and junipers 

 constitute the only species of plants, until we reached the walled town of 

 Djelfa. 



DJELFA TO LAGHOUAT. 



The bleakness and the bareness of the environs of Djelfa come with a 

 surprise when one considers that the rainfall of the place is not inconsider- 

 able, about 375 mm., and that the altitude is about 1,110 meters, which 

 insures a fairly low temperature and hence a relatively low evaporation 

 rate. The sparseness of the vegetation is probably partly due to the fact 

 that the rainfall does not occur at one or at two seasons, as nearer the 

 coast, but is distributed fairly evenly between the four seasons, and also 

 to the long occupancy by the Arabs and the French, by which possibly 

 most of the useful native plants, large and small, have long since been 

 destroyed. Somewhat removed from the town, particularly on the moun- 

 tains to the west, is a forest of pines. Along the streets are many shade 

 trees, as Lombardy poplar, ash, locust, and others, and within the town 

 limits is a small but fine public park and experimental garden with a large 

 variety of shrubs and trees. 



From Djelfa to Laghouat the road runs through barren mountain passes, 

 and is dreary and of little interest . Tristram ' s description of the approach to 

 Laghouat, written about i860, gives very well the present condition of things : 



The next day's journey was through a rocky desert country. . . . We afterwards 

 passed a low-lying strip of sand-hills on the west, with the marks of an ancient ocean 

 beach; on the east a high range of mountains, with the stratification regular and hori- 

 zontal. . . . Our next day's ride was by a base of a continuous chain of steep ridges, 



