NOSTOC

genus of blue-green algae with cells arranged in beadlike chains that are grouped together in a gelatinous mass. Ranging from microscopic to walnut-sized, masses of Nostoc may be found on soil and floating in quiet water. Reproduction is by fragmentation. A special thick-walled cell (akinete) has the ability to withstand desiccation for long periods of time. After 70 years of dry storage, the akinete of one species germinates into a filament when moistened. Like most blue-green algae, Nostoc contains two pigments, blue phycocyanin and red phycoerythrin, and has the ability to fix nitrogen. A terrestrial species is a food source in the East.