Part 2

The Oasis of Ghardaia 38

The Plain (Hamada) of Ghardaia 39

The Mountains about Ghardaia 41

The Valley of the M’Zab 41

Protected Areas near Ghardaia 42

Root-Habits in the Ghardaia Region 44

Leaf-Habits in the Ghardaia Region 49

Growth and Flowering Habits in the Ghardaia Region 49

Ghardaia to Touggourt 50

Ghardaia to Ouargla—Vegetation 53

Ouargla to Touggourt—Vegetation 56

Touggourt to Biskra—Physical Features and Vegetation 58

The Biskra Region 59

Topography 59

Plant Habitats of the Biskra Region 60

Vegetation of the Biskra Region 61

General Summary and Conclusions 66

The Environmental Conditions of Plants in Arid Regions 66

Environmental Features of the Flora of Algeria 69

Some Effects of Temperature and Rainfall in Southern Algeria 71

The Soil Relation in Southern Algeria 73

Root-Characters and Species Distribution in Southern Algeria 76

The Biotic Factor 77

Comparison of Some General Features of the Vegetation of Southern Algeria and of Southern Arizona 79

LIST OF ILLUSTRATIONS. * * * * *

Plate A. Outline map of Algeria, showing main features of surface drainage.

Pl. 1, fig. 1. View of the oasis of Laghouat.

2. Wood market at Laghouat. Juniper, oak, pine, and other kinds of wood, each bunch a camel load, exposed for sale.