From the preceding sketch of the leading topographical conditions
of the vicinity of Biskra it will be seen that the plant habitats
are more diverse than at any other place visited. For the present
purpose the habitats may be distinguished as follows: The alluvial
desert (reg), which lies on every side of the oasis save the north;
low hills adjoining the oasis on the north; Ed Delouatt hills,
southwest; the oueds and their flood-plains; the Dj. Bou Rhezal; the
hamada (?) lying both to the north and to the south of the latter.