Part 20

Illustration: Fig. 64. Tamarix sp. as a sand-binder near Bled-el-Amar, south of Touggourt.

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

Illustration: Fig. 66. Characteristic vegetation on the north slope of the Djebel Bou Rhezal, Biskra. Haloxylon scoparium is a prominent species.

Illustration: Fig. 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.]

Illustration: Fig. 68. Flood-plain of the Oued Hamman es Salahin, Biskra. Halophytes of various species occupy the foreground.

Illustration: Fig. 69. Habitat of Phelypæa violacea shown in figure 70.]

Illustration: Fig. 70. Young shoots of Phelypæa violacea, at north base of Ed Delouatt hills, Biskra.

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

Illustration: Fig. 72. Asphodelus sp. at north base of Ed Delouatt hills, Biskra. Photographed in March.]

Illustration: Fig. 73. Detail of square No. 1, on low hills north of Biskra.

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

Illustration: Fig. 75. Detail of square No. 2, neat area shown in fig. 74. Ferula and Haloxylon are the leading species.

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

Illustration: Fig. 77. Young shoots and mature roots of Ferula vesceritensis. North of Biskra.]

Illustration: Fig. 78. Root-habit of Fagonia growing on edge of a wash. Biskra.

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

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

Illustration: Fig. 81. Spring annuals, March 17th, on north slope of the Djebel Bou Rhezal, Biskra.

Illustration: Fig. 82. Root and shoot habit of Peganum harmala, Biskra. The main root is especially well developed although the species has a generalized root-system. (See text.)]

Illustration: Fig. 83. Annuals growing with Peganum, near Biskra.

Illustration: Fig. 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.]

FOOTNOTES:

+---------+-----------+-------+---------------+ | Season. | Littoral. | Tell. | High plateau. | +---------+-----------+-------+---------------+ | Winter | 41 | 36 | 45 | | Spring | 27 | 32 | 46 | | Summer | 4 | 7 | 11 | +---------+-----------+-------+---------------+

Transcriber's note:

pg 15 Added period after: vegetation of the country

pg 17 Changed: Quercus bollota to: ballota

pg 24 Changed: Rhus oxycantha to: oxyacantha

pg 25 Changed: Artistida pungens to: Aristida