Cylindrospermum
Filamentous cyanobacteria of the nostocales order.
It has the distinction of being able to differentiate two types of specialised cells: Akinetes and heterocysts. Heterocysts are smaller, thick-walled cells. These cells synthesise a nitrogenase to fix atmospheric nitrogen, so cyanobacteria can colonise environments with very low levels of nitrogen. The culture of this strain in a nitrogen-deficient medium induces differentiation in heterocysts. Akinetes are in the subterminal position on the filament.