24 BOTANICAL FEATURES OF THE ALGERIAN SAHARA. 



THE OASIS OF LAGHOUAT. 



The oasis of Laghouat is situated on the Oued Mzi, the upper portion 

 of the Oued Djedi, one of the most important oueds of Algeria. The Oued 

 Djedi runs in an easterly direction from Laghouat, receiving many tribu- 

 tary oueds en route, by a rather long course to the great Chott Melrirh, 

 which is southeast of Biskra. Like other desert rivers, the Oued Djedi is 

 dry most of the year, but is occasionally filled to overflowing with a rush- 

 ing flood, which is of great erosive power and may be very dangerous to 

 the traveler. Above the town of Laghouat, where the Oued breaks through 

 the last pass of the Atlas, the flood-plain is narrow, but upon leaving the 

 pass the plain widens until in the immediate proximity of the town it is 

 about 1.5 kilometers in width. On either side of the flood-plain stretches 

 the arid plain (hamada), usually stony, but near the mountains covered 

 with low, slowly moving sand ridges. To the south of the oasis, the arid 

 plain merges into the topography characteristic of the region of the dayas. 



The portion of the oasis devoted to the cultivation of date and other 

 trees, and to gardens, is about 3 square kilometers in size, but arable land 

 extends above and below the town, so that outside of the oasis, as delimited 

 above, there are about 6 square kilometers, all of which have at times been 

 under cultivation. The last referred to is the flood-plain of the oued and 

 is used mainly for growing barley. By the edge of the oued, or along the 

 irrigating ditches, are several characteristic species of plants, which may 

 point to the character of the primitive flora; for example, willows, oleander, 

 and Tamarix, with a few palms. The betoum {Pistacia atlantica), which 

 must surely have been an inhabitant of the oasis formerly, is now appar- 

 ently wholly absent. The species just mentioned are to be found between 

 the town and the pass above; but below the oasis, owing to an apparently 

 poorer water-supply, there are fewer large species. Among those found 

 are a few specimens of Rhus oxycantha and Zizyphus vulgaris, and it was 

 probably below the town that the betoum was to be found in earlier times. 



The oasis is under intensive cultivation (see fig. i). There are about 300 

 gardens, each bounded by mud walls, and often separated by picturesque, 

 meandering lanes. The plant life, almost wholly introduced, is luxuriant. 

 In some gardens the effect is tropical, where vines reach from tree to tree, 

 making a canopy nearly sun-proof and separating the spreading tops of the 

 palms from the wealth of shrubbery and herbaceous plants beneath. First 

 among the trees of the gardens, in numbers as well as in economic impor- 

 tance, is the date palm, of which there are said to be about 30,000. Although 

 this is small in comparison to the number of date palms at Ouargla, Toug- 

 gourt, or the Oued Rirh, the dates are of great importance to the dwellers 

 at Laghouat, where the products of the gardens are almost all consumed. 

 The living tree provides shelter against the intense heat and light of the 

 desert, and the dead leaves constitute an important source of fuel in a 

 land where fuel is extremely hard to obtain. The flesh of the date fruit 

 is eaten by the Arab and the cracked seeds are given to the camels. With- 



