Lichens: an Obligate Symbiotic Relationship
and Mycorrhizae
and Mycorrhizae
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| SEM of Lichen: the linear fungal hyphae and the round ball-like algal groupings |
The basic structure of a lichen is a mass of fungal hyphae; inbedded in this mass is a zone of algae .
- 25+ different algal species are involved in associations, with the majority of them green algae (although some species are cyanobacteria ( blue-greens)).
- The fungus partner itself is generally an ascomycete, although again many different species of fungi can form this relationship.
- The fungi gain nutrition from the photosynthetic algae while the fungi house and supposedly protect the algae from the elements providing moisture, perhaps protection from the sun and a source of minerals.
- There is some dispute how mutualistic the relationship is. There is a fine line between the role of protector and hostage holder. It may be, that as the algae can do well on their own that the relationship may be less obligate, though certainly intimate. Nutrients may be simply leaking out of the algae; it may be that the fungi is benignly parasitizing the algae.
Mycorrhizae
Mycorrhizae is the relationship between a fungus and a higher plant's root system. In this relationship, the plant feeds the fungus, while the fungus supplies the plant with mineral nutrients ( especially phosphorous) and according to some sources additional moisture.
- This relationship is so important, that some researchers believe the the association formed early in evolution, allowing the first land plants to survive on a soiless, nutrient poor landscape.
- When reestablishing forests in areas decimated by intense logging or forest death due to pollution ( from copper smelting for example) seedlings are first inoculated with spores of symbiotic fungal species to aid in successful reintroduction.
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