190
E. IMRE FRIEDMANN AND MARGALITH GALUN
steppes, semideserts, and deserts. These species, too, represent penetrations
from more moderate environments. It is doubtful if the identifications of
some of the other soil lichens mentioned by Tomin, such as Biatorella fossarum, Candelariella cerinella var. unilocularis, Kelleria polyspora, Placodium ( = Caloplaca) desertorum, Rinodina nimbosa f. sareptana, and
Squamarina muralis f. argilicola, are correct.
An abundance of Lecanora esculenta (Pall.) Eversm., a loose, subfoliose lichen (W ander flechte) in North African and West Asian steppe
regions, has been reported by Elenkin (1901), Eversmann (1831), Keller
(1926), Tomin (1926), and more recently by Klement (1966) in Mongolia. Lecanora esculenta has become legendary by the suggestion that it
is the manna which was eaten by the ancient Israelites during the Exodus
from Egypt. In recent surveys in the Sinai Peninsula, L. esculenta could
not be found (Galun and Garty, 1972; Garty, 1972). Sheep in the Libyan
Desert are reported to graze on L. esculenta (Hale, 1967).
Roccella cervicornis Follm., Farmelia vagans (Nyl.) Nyl., Dermatocarpon vagans Imsh., Tornabenia ephebaea (Ach.) Kur., T. intricata Trevis.,
and Teloschistes brevior f. halophilus (Elenk.) Oxn. [ = T. lacunosa
(Rupr.) Sav.] (Elenkin, 1901; Follmann, 1966; Imshaug, 1950; Klement,
1966), and perhaps Ramalina maciformis (Del.) Bory, belong to the same
ecotype of loose Wanderflechten, in steppe and desert terrain.
Zukal (1896) and Fink (1909) believed that lichen formations of horizontally exposed rocks in regions of average rainfall, as well as those of
perpendicular or inclined southward facing rocks are similar to the lichen
formations of desert rocks.
C. PHYTOGEOGRAPHY
Reichert (1936, 1937a-d, 1940, 1953) studied the lichen vegetation in
steppes and deserts of the Eastern Holarctis in relation to phanerogams
and suggested that the xerofrigid plant formations of Arctic tundras are
characterized by the genus Cladonia (section Cladina); the xerothermic
steppes of the Mediterranean and Irano-Turanian regions are characterized
by Artemisia and species of the genus Diploschistes. Diploschistes steppicus Reich., in particular, represents a very sensitive indicator of this region. In the xerothermic deserts the Zygophyllaceae predominate, accompanied by Ramalina maciformis.
Reichert argues, on the basis of the continental drift theory, that the
Lecanora (Aspicilia) esculenta group originated in the high mountains of
the Irano-Turanian region during the Miocene period, when the eastern
part of the Thetis Sea dried up. During this period the esculenta group,
together with Astragalus tragacantha spp., underwent an extreme xero-
E. IMRE FRIEDMANN AND MARGALITH GALUN
steppes, semideserts, and deserts. These species, too, represent penetrations
from more moderate environments. It is doubtful if the identifications of
some of the other soil lichens mentioned by Tomin, such as Biatorella fossarum, Candelariella cerinella var. unilocularis, Kelleria polyspora, Placodium ( = Caloplaca) desertorum, Rinodina nimbosa f. sareptana, and
Squamarina muralis f. argilicola, are correct.
An abundance of Lecanora esculenta (Pall.) Eversm., a loose, subfoliose lichen (W ander flechte) in North African and West Asian steppe
regions, has been reported by Elenkin (1901), Eversmann (1831), Keller
(1926), Tomin (1926), and more recently by Klement (1966) in Mongolia. Lecanora esculenta has become legendary by the suggestion that it
is the manna which was eaten by the ancient Israelites during the Exodus
from Egypt. In recent surveys in the Sinai Peninsula, L. esculenta could
not be found (Galun and Garty, 1972; Garty, 1972). Sheep in the Libyan
Desert are reported to graze on L. esculenta (Hale, 1967).
Roccella cervicornis Follm., Farmelia vagans (Nyl.) Nyl., Dermatocarpon vagans Imsh., Tornabenia ephebaea (Ach.) Kur., T. intricata Trevis.,
and Teloschistes brevior f. halophilus (Elenk.) Oxn. [ = T. lacunosa
(Rupr.) Sav.] (Elenkin, 1901; Follmann, 1966; Imshaug, 1950; Klement,
1966), and perhaps Ramalina maciformis (Del.) Bory, belong to the same
ecotype of loose Wanderflechten, in steppe and desert terrain.
Zukal (1896) and Fink (1909) believed that lichen formations of horizontally exposed rocks in regions of average rainfall, as well as those of
perpendicular or inclined southward facing rocks are similar to the lichen
formations of desert rocks.
C. PHYTOGEOGRAPHY
Reichert (1936, 1937a-d, 1940, 1953) studied the lichen vegetation in
steppes and deserts of the Eastern Holarctis in relation to phanerogams
and suggested that the xerofrigid plant formations of Arctic tundras are
characterized by the genus Cladonia (section Cladina); the xerothermic
steppes of the Mediterranean and Irano-Turanian regions are characterized
by Artemisia and species of the genus Diploschistes. Diploschistes steppicus Reich., in particular, represents a very sensitive indicator of this region. In the xerothermic deserts the Zygophyllaceae predominate, accompanied by Ramalina maciformis.
Reichert argues, on the basis of the continental drift theory, that the
Lecanora (Aspicilia) esculenta group originated in the high mountains of
the Irano-Turanian region during the Miocene period, when the eastern
part of the Thetis Sea dried up. During this period the esculenta group,
together with Astragalus tragacantha spp., underwent an extreme xero-