[Plate 13:
Illustration: Fig. 31. View in a cemetery at Ghardaia, to show the
relatively abundant vegetation.
Illustration: Fig. 32. View in an M’Zabite cemetery, Ghardaia.
Haloxylon articulatum is the leading species shown.]
[Plate 14:
Illustration: Fig. 33. Habit of Deverra scoparia, from plain about
3km. north of M’Zab Valley, Ghardaia.
Illustration: Fig. 34. Root-habit of Gymnocarpos fruticosum, from
plain about 3km. north of M’Zab Valley, Ghardaia.]
[Plate 15:
Illustration: Fig. 35. Root-habit of a mature specimen of Peganum
harmala, from the floor of the M’Zab Valley near Ghardaia. The soil
at the place is comparatively deep. (See text for further
explanation.)
Illustration: Fig. 36. Root-systems of Helianthemum sessiliflorum
(right), Haloxylon articulatum, and Nolletia chrysocomoides (left),
from the flood-plain of the Oued M’Zab, Ghardaia.]
[Plate 16:
Illustration: Fig. 37. Shoot and root habit of Citrullus colocynthis.
Oued M’Zab, Ghardaia.
Illustration: Fig. 38. Euphorbia guyoniana, in the valley of the Oued
M’Zab at Ghardaia.]
[Plate 17:
Illustration: Fig. 39. Habit of Euphorbia guyoniana. Ghardaia.
Illustration: Fig. 40. To the left, shoot of Centaurea sp., showing
effects of grazing; to the right, shoots of Teucrium
pseudo-chamæpitys. From Ghardaia.]
[Plate 18:
Illustration: Fig. 41. Habit of Salsola sp. (below), and Echinopsilon
muricatus, from the M’Zab Valley, Ghardaia.
Illustration: Fig. 42. Ghardaia to Ouargla. View overlooking the
hamada about 28km. from Ghardaia. The relatively abundant vegetation
is associated with a light cover of sand over the area shown. The
leading species are Aristida, Deverra, and Haloxylon.]
[Plate 19:
Illustration: Fig. 43. Retama retam, in dunes about 58km. from
Ghardaia.
Illustration: Fig. 44. Dates at the bordj Zolfana, about 58km. from
Ghardaia. One of two wells encountered between Ghardaia and Ouargla.
Illustration: Fig. 45. Ghardaia to Ouargla. View overlooking
flood-plain of the Oued M’Zab, or a tributary of this oued. The
adjacent upland is apparently without plant life.]
[Plate 20:
Illustration: Fig. 46. Vegetation on edge of the Oued M’Zab, about
63km. east of Ghardaia, showing habitat of Rhantherium adpressum in
foreground.
Illustration: Fig. 47. Sandy flood-plain of the Oued M’Zab, about 63
km. from Ghardaia. Retama, Genista and Ephedra are the leading plants
in this place.
Illustration: Fig. 48. Habit of Ephedra alata in habitat shown in
figure 47. This specimen was 1.5m. high.]
[Plate 21:
Illustration: Fig. 49. View of habitat of Ephedra alenda, 138km. from
Ghardaia.
Illustration: Fig. 50. Detail of suckering habit of Ephedra alenda,
from habitat shown in figure 49.]
[Plate 22:
Illustration: Fig. 51. Vegetation, mainly Ephedra and Retama, of the
western edge of the Chott Mellala.
Illustration: Fig. 52. Approach to western edge of the Chott Mellala,
showing characteristic rounded hills, or mamelons.]
[Plate 23:
Illustration: Fig. 53. View between the Ouargla plain and the Chott
Mellala, showing characteristic appearance of eroded hills.
Illustration: Fig. 54. Looking toward the Ouargla plain (reg).