Freshwater Algae Key

A1. NONMOTILE ALGAE WITHOUT CHLOROPLASTS: CYANOBACTERIA

A2. NONMOTILE ALGAE WITH CHLOROPLASTS

B1. CELLS USUALLY SOLITARY

B2. NONMOTILE COLONIES WITH TWO OR MORE CELLS

B3. FILAMENTOUS ALGAE (INCLUDING PSEUDOFILAMENTS)

C1. FILAMENTS OR PSEUDOFILAMENTS ATTACHED TO AQUATIC PLANTS (EPIPHYTIC)

C2. CELLS FORM PSEUDOFILAMENTS WHERE THEY ARE ALIGNED END-TO-END BUT NOT JOINED ACROSS THE ENDWALL

C3. UNBRANCHED FILAMENTOUS ALGAE

C4. BRANCHED FILAMENTOUS ALGAE

D1. FILAMENTS WITH DISTINCTLY LARGER PRIMARY BRANCHES AND SMALLER SECONDARY BRANCHES; CELLS IN SECONDARY BRANCHES MAY EXTEND TO FORM LONG, HAIR-LIKE SETAE

D2. FILAMENTS WITH APPROXIMATELY SIMILAR CELLS FORMING PRIMARY AND SECONDARY BRANCHES; FILAMENTS MAY HAVE DISSIMILAR TERMINAL CELLS AND SLIGHTLY LARGER CELLS IN THE MAIN BRANCH

B4. CELLS ATTACHED TO ZOOPLANKTON (EPIZOIC), LIVING INSIDE ZOOPLANKTON OR OTHER AQUATIC ANIMALS (ENDOZOIC), OR ATTACHED TO AQUATIC PLANTS (EPIPHYTIC)

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)