A1. Nonmotile algae without chloroplasts: Cyanobacteriophyta
A2. Motile algae with chloroplasts and flagella
B1. Motile single-cell algae
B2. Motile colonies with 4 or more cells
C1. Cells with two equal flagella in colonies with 4 or more cells
C2. Cells with two dissimilar flagella
A3. Nonmotile algae with chloroplasts but without flagella
A4. Cells with paired, symmetric semi-cells: Desmids
A5. Cells enclosed in glassy, ornamental frustules: Diatoms