The southern spurs of the Saharan Atlas lie to the north of Laghouat,
within 3 miles of the oasis. This range (the Nomad Mountains)
is not over 266 meters in height. Higher mountains extend both to
the west and to the east, but only the Nomads are visited. There
are also two high, rocky hills on opposite edges of the oasis,
the town lying between, and it is perhaps because of their presence
that the water is forced to the surface, or near the surface, and
the oasis is formed. The hill to the west of the town is called
the Rocher des Chiens. On the south side of the Nomad Mountains
is a long outcropping of gypsum; the south face of these mountains
is also abrupt, carrying little soil; but on the northern face the
slope is gradual and there is much soil, although rocks are abundant.
Two localities only in the Nomad Mountains were seen. One was
in a pass through which caravans travel _en route_ to Laghouat,
from the High Plateau or the more distant Tell; the second to the
east of the pass is much less often visited by flocks. The physical
plant conditions appeared to be the same in both locations. As one
approaches the mountains from the south the number of plants grows
less until on the south face they quite disappear, but on attaining
the crest they quickly increase and form a noticeable element in
the landscape. In fact, the flora of the northern gentle slope,
where the soil conditions are relatively favorable, is much richer
than on the plain or the dunes. Had the shrubs been of good size
they would have been very conspicuous.[10]
A certain area on the north slope of the Nomad Mountains, not
far from the pass through which the Oued Mzi goes, was selected
for making a census of the plant population. Here the number
of individuals, as well as their size, showed that the moisture
relations were good as compared with those of the plain. On an
area 16 meters square 422 living perennials were found, mainly of
the following species: _Acanthyllis tragacanthoides_, _Asparagus
spinosa_, _Deverra scoparia_, and _Zollikoferia spinosa_. The most
numerous, _Zollikoferia_, was represented by 96 individuals. The
general character of the habitat and the plants is sufficiently
well shown in fig. 8 and does not need further mention in this place.