A1. Nonmotile algae without chloroplasts: Cyanobacteriophyta
A2. Motile algae with chloroplasts and flagella
A3. Nonmotile algae with chloroplasts but without flagella
A4. Cells with paired, symmetric semi-cells: Desmids
B1. Cells rarely solitary; usually forming clumps or filaments
B2. Cells mostly solitary unless dividing
A5. Cells enclosed in glassy, ornamental frustules: Diatoms