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.