Part 4

Pl. 13, fig. 31. View in a cemetery at Ghardaia, to show the relatively abundant vegetation.

32. View in an M’Zabite cemetery, Ghardaia. Haloxylon articulatum is the leading species shown.

Pl. 14, fig. 33. Habit of Deverra scoparia, from plain about 3 km. north of M’Zab Valley, Ghardaia.

34. Root-habit of Gymnocarpos fruticosum, from plain about 3 km. north of M’Zab Valley at Ghardaia.

Pl. 15, 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.

Pl. 15, fig. 36. Root-systems of Helianthemum sessiliflorum (right), Haloxylon articulatum, and Nolletia chrysocomoides (left), from the flood-plain of the Oued M’Zab, Ghardaia.

Pl. 16, fig. 37. Shoot and root habit of Citrullus colocynthis. Oued M’Zab, Ghardaia.

38. Euphorbia guyoniana, in the valley of the Oued M’Zab at Ghardaia.

Pl. 17, fig. 39. Habit of Euphorbia guyoniana. Ghardaia.

40. To the left, shoot of Centaurea sp., showing effect of grazing; to the right, shoots of Teucrium pseudo-chamæpitys. From Ghardaia.

Pl. 18, fig. 41. Habit of Salsola sp. (below) and Echinopsilon muricatus, from the M’Zab Valley, Ghardaia.

42. Ghardaia to Ouargla. View overlooking the hamada about 28 km. 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.

Pl. 19, fig. 43. Retama retam, in dunes about 58 km. from Ghardaia.

44. Dates at the Bordj Zolfana, about 58 km. from Ghardaia—one of two wells encountered between Ghardaia and Ouargla.

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.

Pl. 20, fig. 46. Vegetation on edge of the Oued M’Zab, about 63 km. east of Ghardaia, showing habitat of Rhantherium adpressum in foreground.

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.

48. Habit of Ephedra alata in habitat shown in figure 47. This specimen was 1.5 m. high.

Pl. 21, fig. 49. View of habitat of Ephedra alenda, 138 km. from Ghardaia.

50. Detail of suckering habit of Ephedra alenda, from habitat shown in figure 49.

Pl. 22, fig. 51. Vegetation, mainly Ephedra and Retama, of the western edge of the Chott Mellala.

52. Approach to western edge of the Chott Mellala, showing characteristic rounded hills, or mamelons.

Pl. 23, fig. 53. View between the Ouargla plain and the Chott Mellala, showing characteristic appearance of eroded hills.

54. Looking toward the Ouargla plain (reg).

55. Shallow well about 25 km. north of Ouargla.

Pl. 24, fig. 56. Ouargla to Touggourt. Leaf-habit of Limoniastrum guyonianum. The surface of the leaves is covered with an incrustation of salts.

57. Habit of Limoniastrum guyonianum. About 25 km. north of Ouargla.

Pl. 25, fig. 58. Vegetation of the reg desert, about 25 km. north of Ouargla. Ephedra and Retama are the leading species of the area—a spreading dune.