Botanical features of the Algerian Sahara — Key Ideas to Explore

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Authors: Cannon, William Austin, 1870-1958 Digital Source: Project Gutenberg Gutenberg Release Year: 2023 First Publication Year: Not confirmed

Key Word: Desert plants -- Sahara; Desert plants -- Algeria; Roots (Botany) Target Reader: Readers of public-domain and historical texts

Book Edition: Project Gutenberg digital edition Book Language: en

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Words 47,674

Reading time 208 min

Text sections 6

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Source: Project Gutenberg record #70581

A 1913 scientific study of plant adaptations in the Algerian Sahara, focusing on root systems, water storage, and species distribution across varied habitats from Laghouat to Ghardaia and Biskra.

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[Plate A: OUTLINE MAP OF ALGERIA SHOWING MAIN FEATURES OF SURFACE DRAINAGE Compiled by G. Sykes, Esq. F. R. G. S.]

Illustration: Fig. 1. View of the Oasis of Laghouat

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

Illustration: Fig. 3. Wood market at Laghouat. Roots of Zizyphus, branches of juniper and pine, and pine bark. The latter is said to be used for staining.]

BOTANICAL FEATURES OF THE ALGERIAN SAHARA

BY WILLIAM AUSTIN CANNON

WASHINGTON, D.C. PUBLISHED BY THE CARNEGIE INSTITUTION OF WASHINGTON 1913

CARNEGIE INSTITUTION OF WASHINGTON PUBLICATION NO. 178

PRESS OF J.B. LIPPINCOTT COMPANY PHILADELPHIA

Geographical Characteristics of Algeria 2

Some Characteristics of the Vegetation of the Tell 15

The Forests of Algeria 18

Boghari to Laghouat 20

Djelfa to Laghouat 22

The Oasis of Laghouat 24

The Dunes near Laghouat 27

The Mountains about Laghouat 28

Effects of Grazing on Vegetation near Laghouat 29

From Laghouat to Ghardaia 31

Region of the Dayas 31

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

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

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.

3. Wood market at Laghouat. Roots of _Zizyphus_, branches of juniper and pine, and pine bark. The latter is said to be used for staining.

Pl. 2, fig. 4. Shoot-habit of _Acanthyllis tragacanthoides_. Laghouat.

5. Shoot-habit of _Zollikoferia spinosa_. Laghouat.

6. _Acanthyllis tragacanthoides_ on sandy plain. Laghouat.

7. _Zollikoferia spinosa_ in habitat, plain (hamada). Laghouat.

Pl. 3, fig. 8. Detail of north slope of Nomad Mountains, where _Zollikoferia spinosa_ is the dominant species. Laghouat.

9. Vegetation of plain (hamada) at Tilrempt. The conspicuous shrub is _Haloxylon articulatum_.

10. The daya of Tilrempt from the plain, showing the character of the depression.

Pl. 4, fig. 11. Near view of the daya of Tilrempt. The fortified stage station, bordj, and a nomad camp are to be seen. The flattened, level, lower surface of the trees is the effect of grazing, mainly by camels.

12. Jujube (_Zizyphus_) shrubs and betoum (_Pistacia_) at the daya of Tilrempt.

Pl. 5, fig. 13. A young specimen of betoum in the midst of a protecting jujube at the daya of Tilrempt.

14. Leaf and shoot habit of the jujube (_Zizyphus lotus_). Daya of Tilrempt.

15. Leaves of the betoum (_Pistacia atlantica_) from the daya of Tilrempt.

Pl. 6, fig. 16. South wall of the valley of the Oued M’Zab at Ghardaia.

17. Detail of an eroded bank of the Oued M’Zab at Ghardaia. The overhanging stratum is hardpan similar to the “caliche” of southwestern United States.

Pl. 7, fig. 18. Shoot-habit of _Haloxylon articulatum_, from the plain near the daya of Tilrempt.

19. Agriculture at Ghardaia. The fields are divided into plots about 3 by 4 feet in size, for the more economical use of water. Young barley is shown growing (November).

Pl. 8, fig. 20. Vegetation in upper part of a “draw” on plain north of the M’Zab Valley, Ghardaia.

21. Situation of square No. 2, on plain north of valley at Ghardaia.

Pl. 9, fig. 22. _Capparis spinosa_ at base of valley wall at Ghardaia.

23. Leaves of _Capparis spinosa_ from Ghardaia.

Pl. 10, fig. 24. Leaf-habit of _Dæmia cordata_. Ghardaia.

25. Shoot-habit of _Salvia ægyptica_. Ghardaia.

26. Upper surface of rocks, showing small incrusting lichens, on a low mountain about 5 km. north of M’Zab Valley, Ghardaia.

Pl. 11, fig. 27. Habitat of _Peganum harmala_, at Melika, Ghardaia.

28. Shoot and leaf habit of _Peganum harmala_, from Ghardaia.

Pl. 12, fig. 29. Habit of _Henophyton deserti_ at Ghardaia when growing in a protected situation (cemetery).

30. Leaf-habit of _Henophyton deserti_. Ghardaia.

Pl. 13, fig. 31. View in a cemetery at Ghardaia, to show the relatively abundant vegetation.

32. View in an M’Zabite cemetery, Ghardaia. _Haloxylon articulatum_ is the leading species shown.

Pl. 14, fig. 33. Habit of _Deverra scoparia_, from plain about 3 km. north of M’Zab Valley, Ghardaia.

34. Root-habit of _Gymnocarpos fruticosum_, from plain about 3 km. north of M’Zab Valley at Ghardaia.

Pl. 15, fig. 35. Root-habit of a mature specimen of _Peganum harmala_, from the floor of the M’Zab Valley near Ghardaia. The soil at the place is comparatively deep.

Continue Reading →

William Austin Cannon's 1913 study, published by the Carnegie Institution, examines how plants survive in the Algerian Sahara through detailed field observations. Rather than a general survey, the work concentrates on specific root architectures and their relation to soil conditions, grazing pressure, and water availability. Cannon's method involves digging up specimens and measuring root depth, branching patterns, and storage organs, as seen in his sketches of Peganum harmala, Haloxylon articulatum, and Euphorbia guyoniana.

The text moves systematically from the Tell region through the High Plateau to the desert oases, with particular attention to the Ghardaia and Biskra areas. Cannon compares his findings with vegetation in southern Arizona, offering a comparative perspective on arid-land plant ecology.

Root Systems as Adaptive Signatures

Cannon's primary evidence comes from excavated root systems. He distinguishes between tap-root types, like Henophyton deserti with a root extending 75 cm without laterals, and generalized types that spread widely but shallowly. For Peganum harmala, he notes that roots do not penetrate deeply even in deep soil, instead reaching laterally. In contrast, Haloxylon articulatum shows a well-developed main root descending more than 30 cm, though its shoots are often damaged by grazing animals.

The most striking adaptation appears in Euphorbia guyoniana, which reproduces vegetatively from horizontally placed fleshy roots that serve as water- and food-storage organs. Cannon observes that only two other species in the Ghardaia region—Citrullus colocynthis and Phelypæa violacea—exhibit similar storage capacity. These observations are grounded in specific measurements: root diameters of 8 mm for the main root-stock and 3–5 mm for branches, with shoots only 15 cm high.

Grazing, Protection, and Plant Form

Cannon repeatedly notes the impact of livestock on plant morphology. When describing Haloxylon articulatum, he remarks that its gnarled base indicates intermittent animal attacks, and that finding undamaged specimens required searching in protected areas. The text mentions a dedicated section on "Protected Areas near Ghardaia" (pages 42–43), suggesting Cannon deliberately compared plants inside and outside exclosures.

This biotic factor—grazing—shapes not only shoot form but also root development. Cannon implies that plants under grazing pressure may allocate resources differently, though he does not fully elaborate. The wood market at Laghouat, illustrated in Plate 1, shows juniper, oak, pine, and Zizyphus roots sold as fuel, indicating human use of woody plants. Cannon's attention to these pressures makes the study an early contribution to understanding human and animal impacts on desert vegetation.

Soil, Hardpan, and Species Distribution

Cannon correlates root types with soil conditions. In habitats where hardpan approaches the surface, he finds that Peganum harmala develops a less prominent main root but more laterals compared to specimens in deeper soil. Similarly, Euphorbia guyoniana grows more abundantly on the southern side of an oued where soil is cemented into hardpan, often in groups or singly. This suggests that soil cementation favors vegetative reproduction and storage roots.

The study also notes that Tamarix specimens over 3 meters high, growing in deep sand, exhibit a tap-root type with an unbranched main root descending directly. These observations, combined with measurements of root depth and lateral spread, provide a quantitative basis for understanding how soil texture and depth influence root architecture. Cannon's comparison with Covillea tridentata (creosote bush) in Arizona underscores the generality of these patterns across arid regions.

Cannon's work rewards readers who attend to his precise measurements and habitat descriptions. The root sketches and soil notes offer a concrete basis for understanding plant survival strategies, while the comparisons with Arizona vegetation invite broader ecological thinking. Readers interested in desert botany, plant adaptation, or early 20th-century field methods will find this a valuable primary source.

Reading about those Saharan roots reaching for water, I remembered a dry Utah summer and the small stubborn flowers I found there, thriving on almost nothing. Wild Flowers of Zion and Bryce Canyon National Parks and Cedar Breaks National Monument — Inside the Classic held that same quiet astonishment—life persisting in stone, patient and unbothered by the sun.