Taxobox | name = "Geosiphon pyriformis"
regnum = Fungi
genus = "Geosiphon"
subdivision_ranks = Species
subdivision = "Geosiphon pyriformis"
"Geosiphon pyriformis" is known for being the
symbiontof " Nostoc". The "Geosiphon"-" Nostoc" symbiosis, as by modern definitions, is not a lichen, since it is an intracellular association. Also, by functional and evolutionary implications it is more comparable to the arbuscular mycorrhiza symbioses than to lichens.
Nostoc" symbiosis is the only known fungal endosymbiosis with cyanobacteria and is characterised by a "siphonal bladder" that is made of a swollen fungal hypha, 0.5-2 mm in size and growing on the soil surface. The upper 2/3 of the "bladder" contains the "Nostoc" filaments and Nostoc heterocysts, the lower 1/3 is filled with lipiddroplets.
spores are 250 micrometres in diameter, formed at the end of one hypha, or intercalarly (within a hyphae) and resemble those of members of the Glomeromycota.
"Geosiphon" has a specialised bladder used to harbour
cyanobacteria. "Geosiphon pyriformis" is not known to form arbuscular mycorrhiza.
*C.J. Alexopolous, Charles W. Mims, M. Blackwell, "Introductory Mycology, 4th ed." (John Wiley and Sons, Hoboken NJ, 2004) ISBN 0-471-52229-5
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