Nostoc coeruleum.

Nostoc coeruleum is a Cyanophyte which can grow up to quite a large size (1cm). This colony was photographed in phase contrast on a Zeiss photomicroscope 111. Photograph (a) shows a complete ball which could be seen with the naked eye.Photograph (b) shows a close up of the same colony but squashed flat to see the cells more clearly.Photograph ( c ) was taken to show the mucilage that surrounds the filaments and also the many bacteria that seem to thrive within the surrounding coat. This specimen was collected from Oak plain pond in Epping Forest in the month of May 2002. According to West & Fritsch this Cyanophyte can be found all over Britain.

Unidentified species of Nostoc.

These colonies of Nostoc was very numerous in a small steam in northern California. Unfortunatly I did not have a microscope with me at the time so a closer inspection was not possible.