Freshwater Algae Key

A1. NONMOTILE ALGAE WITHOUT CHLOROPLASTS: CYANOBACTERIA

B1. VEGETATIVE CELLS USUALLY SOLITARY

B2. VEGETATIVE CELLS UNITED INTO COLONIES

C1. CELLS ARRANGED IN A SINGLE LAYER FORMING FLAT COLONIES

C2. CELLS ARRANGED IN CUBICAL COLONIES

C3. CELLS ARRANGED IN SPHERICAL OR NEARLY SPHERICAL COLONIES

C4. CELLS ARRANGED INTO IRREGULAR, AMORPHOUS COLONIES

D1. CELLS APPEAR BROWN AND MOTTLED UNDER MICROSCOPE

D2. CELLS DO NOT APPEAR BROWN AND MOTTLED UNDER MICROSCOPE

E1. CELLS SPHERICAL OR OVAL

E2. CELLS ELLIPTICAL, ROD-SHAPED, CYLINDRICAL, OR FUSIFORM

B3. VEGETATIVE CELLS ALIGNED END-TO-END FORMING FILAMENTS OR PSEUDOFILAMENTS

A2. NONMOTILE ALGAE WITH CHLOROPLASTS

A3. MOTILE ALGAE WITH CHLOROPLASTS AND FLAGELLA

A4. CELLS DIVIDED INTO MIRROR-IMAGE SEMI-CELLS: Desmids (see key at cedar.wwu.edu/cedarbooks/14/ )

A5. CELLS ENCLOSED IN GLASSY, ORNAMENTAL FRUSTULES: Diatoms (see key at diatoms.org)