IV. DESERT ALGAE, LICHENS, AND FUNGI
199
The cultured phycobiont is less resistant to high temperatures than the
algae in the thallus. However, a correlation between the habitat and the
degree of resistance exists in cultivated algae similar to that found for the
intact thallus (Lange, 1953). There are no data on the degree of resistance
of the cultured mycobiont.
The studies of Lange and collaborators have shed much light on the
problem of water relations and their consequences in lichens and have resolved some conflicting views concerning this subject in the earlier literature. Jumelle (1892) could not observe differences in the behavior of the
free-living algae and the phycobiont of the lichen thallus. He, therefore,
refuted a previous assumption by van Tieghem (1874) that the algal component of the thallus is protected by the surrounding hyphae. The report
by Thomas (1921) on the survival of a crustose lichen from Libya after
a 5-year period of drought is based on visual observation and is therefore
rather doubtful. Follmann (1965b) assumes that the relatively large
amount of lichenin and protein, which he found in the Atacama Desert
lichens, slows down the rate of dehydration.
Blyum (1964, 1965) studied the rate of water reserve consumption in
several foliose, fruticose, and crustose lichens from "meso- and xerotic
habitats." He concluded that the rate of water reserve consumption is not
always correlated with the nature of the habitat and that xeromorphic
adaptations do not always function as a protection against evaporation.
III. Desert Fungi
A. INTRODUCTION
Most of the information available on desert fungi concerns soil micromycetes although higher fungi also occur in deserts. Micromycetes may
also be present on desert rock substrates, but at this time nearly nothing
is known about these organisms. The micromycete parasites of desert
plants are not considered in this review.
B. SOIL MICROMYCETES: FLORA
Killian and Fehér (1939) listed 38 species of fungi in their pioneering
work on the Sahara soil microflora and described Aspergillus, Pénicillium,
Syncephalastrum, and Trichoderma as the most characteristic genera. Unfortunately, the usefulness of their data is rather limited, due to inexact
taxonomy. In later studies on Sahara soils, Nicot (1955, 1960) found
that the mycoflora of the pure sands of the Grand Erg dunes is very sparse
199
The cultured phycobiont is less resistant to high temperatures than the
algae in the thallus. However, a correlation between the habitat and the
degree of resistance exists in cultivated algae similar to that found for the
intact thallus (Lange, 1953). There are no data on the degree of resistance
of the cultured mycobiont.
The studies of Lange and collaborators have shed much light on the
problem of water relations and their consequences in lichens and have resolved some conflicting views concerning this subject in the earlier literature. Jumelle (1892) could not observe differences in the behavior of the
free-living algae and the phycobiont of the lichen thallus. He, therefore,
refuted a previous assumption by van Tieghem (1874) that the algal component of the thallus is protected by the surrounding hyphae. The report
by Thomas (1921) on the survival of a crustose lichen from Libya after
a 5-year period of drought is based on visual observation and is therefore
rather doubtful. Follmann (1965b) assumes that the relatively large
amount of lichenin and protein, which he found in the Atacama Desert
lichens, slows down the rate of dehydration.
Blyum (1964, 1965) studied the rate of water reserve consumption in
several foliose, fruticose, and crustose lichens from "meso- and xerotic
habitats." He concluded that the rate of water reserve consumption is not
always correlated with the nature of the habitat and that xeromorphic
adaptations do not always function as a protection against evaporation.
III. Desert Fungi
A. INTRODUCTION
Most of the information available on desert fungi concerns soil micromycetes although higher fungi also occur in deserts. Micromycetes may
also be present on desert rock substrates, but at this time nearly nothing
is known about these organisms. The micromycete parasites of desert
plants are not considered in this review.
B. SOIL MICROMYCETES: FLORA
Killian and Fehér (1939) listed 38 species of fungi in their pioneering
work on the Sahara soil microflora and described Aspergillus, Pénicillium,
Syncephalastrum, and Trichoderma as the most characteristic genera. Unfortunately, the usefulness of their data is rather limited, due to inexact
taxonomy. In later studies on Sahara soils, Nicot (1955, 1960) found
that the mycoflora of the pure sands of the Grand Erg dunes is very sparse