Anabaena variabilis is a phylogenic-cousin of the more well-known species Nostoc spirrilum. Both of these species along with many other cyanobacteria are known to form symbiotic relationships with plants. Other cyanobacteria are known to form symbiotic relationships with diatoms, though no such relationship has been observed with Anabaena variabilis.
Anabaena variabilis is also a model organism for studying the beginnings of multicellular life due to its filamentous characterization and cellular-differentiation capabilities.
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Islam, MS; Drasar, BS; Bradley, DJ (1990). "Long-term persistence of toxigenic Vibrio cholerae 01 in the mucilaginous sheath of a blue-green alga, Anabaena variabilis". The Journal of Tropical Medicine and Hygiene93 (2): 133–9. PMID2109096.
Pearce, J.; Leach, C. K.; Carr, N. G. (1969). "The Incomplete Tricarboxylic Acid Cycle in the Blue-green Alga Anabaena Variabilis". Journal of General Microbiology55 (3): 371–8. doi:10.1099/00221287-55-3-371. PMID5783887.