Filaments result from cell division in the plane perpendicular to the axis of the filament and have
cell chains consisting of daughter cells connected to each other by their end wall. Filaments can be
simple as in Oscillatoria (Cyanophyta) (Figure 1.7), Spirogyra (Chlorophyta) (Figure 1.8), or Ulothrix (Chlorophyta) (Figure 1.9), have false branching as in Tolypothrix (Cyanophyta)
(Figure 1.10) or true branching as in Cladophora (Chlorophyta) (Figure 1.11). Filaments of Stigonema ocellatum (Cyanophyta) (Figure 1.12) consists of a single layer of cells and are
called uniseriate, and those of Stigonema mamillosum (Cyanophyta) (Figure 1.13) made up of
multiple layers are called multiseriate.