Part 5

59. Shoot-habit of Halocnemon strobilaceum. About 28 km. north of Ouargla.

Pl. 26, fig. 60. Habit of Halocnemon strobilaceum on the edge of a chott, about 28 km. north of Ouargla.

61. Shoot and leaf habit of Anabasis articulata, about 32 km. north of Ouargla.

Pl. 27, fig. 62. Detail of the shoot-habit of Salsola tetragona?, about 25 km. north of Ouargla.

63. Habit of Nolletia chrysocomoides near the edge of a chott, about 80 km. north of Ouargla.

Pl. 28, fig. 64. Tamarix sp. as a sand-binder near Bled-el-Amar, south of Touggourt.

65. Biskra. Habitat of Euphorbia guyoniana, looking toward the Djebel Maouya, with the Chaine de Sfa in the background.

Pl. 29, fig. 66. Characteristic vegetation on the north slope of the Djebel Bou Rhezal, Biskra. Haloxylon scoparium is a prominent species.

67. North base of Ed Delouatt hills, west of Biskra, showing the low facing dunes. To the right is a glimpse of an oued which pierces the hills in the middle distance.

Pl. 30, fig. 68. Flood-plain of the Oued Hamman es Salahin, Biskra. Halophytes of various species occupy the foreground.

69. Habitat of Phelyæa violacea shown in figure 70.

Pl. 31, fig. 70. Young shoots of Phelypæa violacea, at north base of Ed Delouatt hills, Biskra.

71. Habit of young specimens of Phelypæa. Except for about 15 cm., plants were buried by sand. Biskra.

Pl. 31, fig. 72. Asphodelus sp. at north base of Ed Delouatt hills, Biskra. Photographed in March.

Pl. 32, fig. 73. Detail of square No. 1, on low hills north of Biskra.

74. Vegetation of north slope of the low hills which are north of Biskra. Ferula vesceritensis is the perennial appearing in the figure.

Pl. 33, fig. 75. Detail of square No. 2, near area shown in fig. 74. Ferula and Haloxylon are leading species.

76. Root-habit of Haloxylon scoparium, from a wash near Biskra.

77. Young shoots and mature roots of Ferula vesceritensis. North of Biskra.

Pl. 34, fig. 78. Root-habit of Fagonia growing on edge of a wash. Biskra.

79. Large lateral root of Haloxylon, with numerous deciduous rootlets, no longer functional.

80. Shoot-habit, taken from above, of Fagonia from the flood-plain of a small oued near Biskra.

Pl. 35, fig. 81. Spring annuals, March 17, on north slope of the Djebel Bou Rhezal, Biskra.

82. Root and shoot habit of Peganum harmala, Biskra. The main root is especially well developed, although the species has a generalized root-system.

Pl. 36, fig. 83. Annuals growing with Peganum, near Biskra.

84. General view of the north face of the Djebel Bou Rhezal, Biskra. Apparently barren, plants are rather numerous in the rock crevices and small washes of the mountains.

BOTANICAL FEATURES OF THE ALGERIAN SAHARA.

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