IV. DESERT ALGAE, LICHENS, AND FUNGI
191
phytic transformation. The esculenta and tragacantha vegetation migrated
from Central Asia to the west and to the south; while the tragacantha
group stopped at the Balkans, the esculenta group further migrated to
North Africa through the ancient Italic Bridge. The "desert forms" of the
esculenta group are according to Elenkin (1901), desertoides Elenk.,
foliacea Elenk., and esculenta-tesquina (Pall.) Elenk.
It seems that within a particular area the substrate has a crucial influence on lichen settlement. According to Galun (1963), the lichen population of the Irano-Turanian and the Saharo-Sindian region in the Negev
Desert can be subdivided according to the substrate on which they grow.
The lichen population of the Irano-Turanian region is composed of
1. Terrestial species
a. species characteristic of this region
b. species not characteristic of this region
2. Saxicole species, all of them not characteristic of this region
a. growing on flint
b. growing on calcareous stones
The lichen population of the Saharo-Sindian region in the Negev Desert
is composed of
1. Terrestrial species, all of them not characteristic of this region
2. Saxicole species
a. growing on flint
i. characteristic
ii. not characteristic
b. growing on calcareous stones
i. characteristic
ii. not characteristic
According to Faurel et al (1953) 30% of the 114 lichen species found
in the Algerian Sahara are endemic to North Africa, while 2 1 % are restricted to the Algerian Sahara only. Weber (1962) is of the opinion that
a misunderstanding of environmental modificants has led to a belief in a
great amount of local endemisms. He points out the high correlation between the lichens of the Southwestern American desert and the deserts of
Central Asia (as reported by Magnusson, 1944) and states that ". . . the
correlations may be extended in part to include the deserts of North Africa,
South America and Australia." Follmann (1965a) indicates that the
lichens of the Atacama Desert belong to the same families as those mentioned by Doidge (1950) and Vogel (1955) in the South African Little
Karroo Desert and Namaqualand, namely, Buelliaceae, Dermatocarpaceae,
191
phytic transformation. The esculenta and tragacantha vegetation migrated
from Central Asia to the west and to the south; while the tragacantha
group stopped at the Balkans, the esculenta group further migrated to
North Africa through the ancient Italic Bridge. The "desert forms" of the
esculenta group are according to Elenkin (1901), desertoides Elenk.,
foliacea Elenk., and esculenta-tesquina (Pall.) Elenk.
It seems that within a particular area the substrate has a crucial influence on lichen settlement. According to Galun (1963), the lichen population of the Irano-Turanian and the Saharo-Sindian region in the Negev
Desert can be subdivided according to the substrate on which they grow.
The lichen population of the Irano-Turanian region is composed of
1. Terrestial species
a. species characteristic of this region
b. species not characteristic of this region
2. Saxicole species, all of them not characteristic of this region
a. growing on flint
b. growing on calcareous stones
The lichen population of the Saharo-Sindian region in the Negev Desert
is composed of
1. Terrestrial species, all of them not characteristic of this region
2. Saxicole species
a. growing on flint
i. characteristic
ii. not characteristic
b. growing on calcareous stones
i. characteristic
ii. not characteristic
According to Faurel et al (1953) 30% of the 114 lichen species found
in the Algerian Sahara are endemic to North Africa, while 2 1 % are restricted to the Algerian Sahara only. Weber (1962) is of the opinion that
a misunderstanding of environmental modificants has led to a belief in a
great amount of local endemisms. He points out the high correlation between the lichens of the Southwestern American desert and the deserts of
Central Asia (as reported by Magnusson, 1944) and states that ". . . the
correlations may be extended in part to include the deserts of North Africa,
South America and Australia." Follmann (1965a) indicates that the
lichens of the Atacama Desert belong to the same families as those mentioned by Doidge (1950) and Vogel (1955) in the South African Little
Karroo Desert and Namaqualand, namely, Buelliaceae, Dermatocarpaceae,