III. PHYSICAL AND VEGETATIONAL ASPECTS OF THE SAHARA
145
Fig. 24. The spiny bush of Launea arborescens, a Compositae without leaves.
en care of in a unique manner. The leaves curl along their axis and form
a hollow cylinder with the stomata now on the inside curled surface.*
The general form of the plant can be modified to reduce overheating.
The leaves extend parallel not perpendicular to the rays of the sun, as
is the case in other areas of the world. The plant can take on the aspect
of a ball or a small cushion; this is a defense against the high intensity of
the solar radiation and the violence of the wind. One of the most characteristic of such plants, Anabasis aretioides, has a dense distribution of
branches (see Fig. 25). This Chenopodiaceae, commonly called cauliflower
of Bou-Hammama or desert cauliflower, is ideally adapted to life in the
desert. Its area of distribution is limited to a restricted zone of the north
occidental Sahara. The more or less hemispherical shape resembles a
mossy boulder. The trunk and the principal branches are stunted; distally
they trap sand between them, and as the branches atrophy, the spiny leaves
form a peripheral crust. The dried trunk is excellent firewood. The external
crust, carefully cut, is given to sheep and camels to eat. In areas devoid
* This configuration of the leaf, as well as the presence of bulbiferous cells above
the stomata and stomatiferous furrows with sunken stoma protected by bristles and a
chamber or well, serves to reduce the movement of air and the loss of water by
evaporation.
145
Fig. 24. The spiny bush of Launea arborescens, a Compositae without leaves.
en care of in a unique manner. The leaves curl along their axis and form
a hollow cylinder with the stomata now on the inside curled surface.*
The general form of the plant can be modified to reduce overheating.
The leaves extend parallel not perpendicular to the rays of the sun, as
is the case in other areas of the world. The plant can take on the aspect
of a ball or a small cushion; this is a defense against the high intensity of
the solar radiation and the violence of the wind. One of the most characteristic of such plants, Anabasis aretioides, has a dense distribution of
branches (see Fig. 25). This Chenopodiaceae, commonly called cauliflower
of Bou-Hammama or desert cauliflower, is ideally adapted to life in the
desert. Its area of distribution is limited to a restricted zone of the north
occidental Sahara. The more or less hemispherical shape resembles a
mossy boulder. The trunk and the principal branches are stunted; distally
they trap sand between them, and as the branches atrophy, the spiny leaves
form a peripheral crust. The dried trunk is excellent firewood. The external
crust, carefully cut, is given to sheep and camels to eat. In areas devoid
* This configuration of the leaf, as well as the presence of bulbiferous cells above
the stomata and stomatiferous furrows with sunken stoma protected by bristles and a
chamber or well, serves to reduce the movement of air and the loss of water by
evaporation.