Classification
 
Domain – Bacteria
Phylum - Cyanobacteria
Order - Nostocales
Family - Nostocaceae
Genus - Nostoc
SpeciesN. calcicola, N. commune,
    N. cycadae, N. desertorum,
    N. edaphicum, N. ellipsosporum,
    N. entophytum, N. flagelliforme,
    N. indistinguenda, N. lichenoides,
    N. linckia, N. muscorum,
    N. paludosum, N. piscinale,
    N. punctiforme, N. sphaericum,
    N. trichormus
picture by Paul James, click for original site
First, Nostoc falls under the Domain Bacteria. It is an organism with a  prokaryotic cell structure with cell walls containing peptidogylcan. It has no internal membrane bound structures, or organelles, and the genetic material is not found within a nucleus. The Phylum Cyanobacteria is composed of photosynthetic bacteria. Nostoc then falls into the Order Nostocales because it has non-branching filiments and is futher separated into the Family Nostocaceae for having special nitrogen fixing heterocysts. Finally, we come to the Genus Nostoc, which contains organisms that form spherical colonies of filaments embedded in a gelatinous substance.
Spirochaeles
 
Chalamdiales
 
High-GC Gram Positives
 
Cyanobacteria
 
Low-GC Gram Positives
 
Proteobacteria
Bacteria
Phylogenetic Tree of Domain Bacteria
Nostoc
Not enough bacteria for ya? Check out these other great webpages made by college students like me. 
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       - Watch out!  it can be a pain in the foot! http://bioweb.uwlax.edu/bio203/s2008/arnold_meaghttp://bioweb.uwlax.edu/bio203/s2007/allmann_ambehttp://bioweb.uwlax.edu/bio203/s2007/falk_petehttp://bioweb.uwlax.edu/bio203/s2007/falk_peteshapeimage_16_link_0shapeimage_16_link_1shapeimage_16_link_2shapeimage_16_link_3