In this section
Multiple cyanobacterial isopolar filaments enclosed within a mucilaginous sheath. Filaments usually not tapered at the ends, or if so, only over the length of a few cells. Terminal cell may be conical, but lacking calyptra (thickened cap). Cells cylindrical, usually longer than wide, blue-green or blue. False branching common. Heterocytes and akinetes absent. Organelles absent from the cells.