endosymbiotic cyanobacteria which are found in the leaf pockets of Azolla and the
coralloid roots of cycads. What follows is the information that I received from him
regarding these cyanobacterial endosymbionts:
Fig. 26.21 The water fern Azolla and its symbiont Anabeana. Water ferns of the genus Azolla, also
called mosquito ferns, contain leaf pockets in which are housed symbiotic cyanobacteria of the
genus Anabeana. The Anabeana provide fixed nitrogen to the plant. The upper image is titled
“Azolla caroliniana.jpg” by author Ingrid Taylar from San Francisco Bay Area—California, USA,
and it is being used under a Creative Commons Attribution 2.0 Generic license. The lower image is
titled “Azolla lvs LS with Anabaena.jpg” with the provided description “Light micrograph of a
longitudinal section of Azolla, showing the cyanobacterium Anabaena in leaf pockets” by author
Curtis Clark and is being used under a Creative Commons Attribution-Share Alike 3.0 Unported
license. In this lower image, the Anabaena are visible as a band of dark cells lining the interior of the
leaf pockets
26 The Game of Evolution Is Won by Competitive Cheating
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