Freshwater Algae Key

A1. Nonmotile algae without chloroplasts: Cyanobacteriophyta

A2. Motile algae with chloroplasts and flagella

B1. Motile single-cell algae

C1. Cells with one visible flagellum

D1. Cells covered with scales (scaled chrysophytes); most species also have long spines: Mallomonas

D2. Cells enclosed in a rigid lorica

D3. Cells not covered with scales or enclosed in a lorica; may be rigid or flexible

E1. Cells resemble Euglena but are usually epizoic on freshwater microcrustaceans: Colacium

E2. Cell wall flexible; cells often exhibit worm-like or amoeboid movement in addition to flagellar movement

E3. Cell wall rigid

C2. Cells with two equal length flagella

C3. Cells with two dissimilar flagella

C4. Cells with more than two flagella

B2. Motile colonies with 4 or more cells

A3. Nonmotile algae with chloroplasts but without flagella

A4. Cells with paired, symmetric semi-cells: Desmids

A5. Cells enclosed in glassy, ornamental frustules: Diatoms