In this section
Blue-green isopolar cyanobacterial filaments encased in a yellow-brown mucilage sheath. False branching is characteristically at right-angle bends, either forming a loop (prior to division) or two parallel branches at right angles to the original filament. Heterocytes cylindrical to barrel-shaped, intercalary, located throughout the filaments. Organelles absent from the cells, but granules/vesicles common.