Summary 2

Anabaena is a genus of filamentous cyanobacteria that may be found in phytoplankton assemblages or mixed with shoreline vegetation in lakes and ponds. It is known for its nitrogen fixing abilities; one species (Anabaena azollae, which was renamed Trichormus azollae) forms a symbiotic relationship with the mosquito fern (Azolla).

The taxonomy for Anabaena is currently in a state of flux and a newer genus name, Dolichospermum, is now used for most of the planktonic species, including many of the toxin-forming species. For more information on the Dolichospermum / Anabaena group please see:

About 3

This guide was prepared by Dr. Robin Matthews, former Director of the Institute for Watershed Studies ( and professor emeritus at Western Washington University. In addition to this guide she has also written two ebooks (more on the way) on phytoplankton identification (see the "algae books" link on and an online key to the cyanobacteria (

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  1. (c) rmatth, some rights reserved (CC BY-NC-SA), uploaded by rmatth
  2. Adapted by Bryan Milstead from a work by (c) Wikipedia, some rights reserved (CC BY-SA),
  3. Adapted by rmatth from a work by (c) Bryan Milstead, some rights reserved (CC BY-NC-SA)

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