Leaving Ouargla by the western gate and turning north, we soon passed through the crooked streets and reached the reg desert to the north. There is little vegetation near Ouargla, but on some low dunes extending over the reg we found _Aristida pungens_ and _Phragmites_ sp., growing in a hollow. On the flood-plain there were a large number of individuals and probably a large number of species. Among the most conspicuous of the shrubs were _Retama retam_ and _Limoniastrum guyonianum_, the “zaita” of the Arabs. (See figs. 56 and 57.) Zaita is a handsome shrub with cylindrical leaves often covered with a fairly heavy salt incrustation. So abundant is the exudation that in localities where the species is especially abundant, as at our camp 32 kilometers south of Touggourt, the plants have the appearance of being covered with snow. Although, like many other species between Touggourt and Ouargla, zaita can live where there are salts in excess, it appears not to be an extreme type of halophyte and does not occur where the salts are most dense. It was seen both on the dunes and on the low lands. Other common halophytes are “souid” (_Salsola tetragona_), “belbel” (_Anabasis_ sp.), and _Halocnemon strobilaceum_, which appears especially resistant. (See figs. 59, 60, 61, and 62.) Other forms appear on the higher ground and on the plain about 50 kilometers from Ouargla, where _Ephedra alata_ especially is common. There are no dunes on the plain, but some sand swept across it from the fluvial desert to the west passes eastward and augments the dunes farther east. The larger specimens of _Ephedra_ are rather effective sand-binders and bring about the formation of diminutive dunes. The effect on the growth of the species by the piling sand is peculiar. As the sand accumulates it covers the lower branches of the shoot; these are stimulated to unusual growth and new branches may spring from them. Thus the effect is similar to that habitually occurring in _E. alenda_, but in _E. alata_ the habit is not a fixed one. As an instance of the length which such submerged branches may attain, it may be mentioned that one, 2 to 3 cm. in diameter, was over 4 meters long. About 75 kilometers from Ouargla, and on a plain similar to that just referred to, “dhamran” (_Traganum nudatum_) was the most common species, but was by no means abundant. The census of an area 16 by 16 meters, taken in a locality where dhamran was dominant, resulted in finding 31 living and a few dead plants, probably all _Traganum_. It is to be understood that the vegetation of the reg desert not far distant is much richer, not only in species but especially in individuals, and also that the plants are much larger. From 56 kilometers to about 71 kilometers from Ouargla the route lay over more or less continuous dunes, where the leading species seen were _Aristida_ sp., _Ephedra_ sp., _Euphorbia guyoniana_, _Limoniastrum guyonianum_, and _Traganum nudatum_.