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)

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

C1. CELLS ATTACHED TO ZOOPLANKTON (EPIZOIC) OR LIVING INSIDE ZOOPLANKTON OR OTHER AQUATIC ANIMALS (ENDOZOIC)

C2. CELLS SOLITARY, ATTACHED TO AQUATIC PLANTS (EPIPHYTIC)

C3. CELLS FORMING COLONIES; ATTACHED TO PLANTS (EPIPHYTIC)

D1. COLONIES PARASITIC ON TREE POLLEN; CELLS PYRAMIDAL, WITH A SHORT APICAL SPINE, OFTEN LACKING CHLOROPHYLL; CELLS JOINED BY SHORT EXTENSIONS TO FORM OPEN, SPHERICAL COLONY: Ducellieria

D2. CELLS WITH LONG HAIR-LIKE SETAE OR PSEUDOCILIA; SOLITARY OR IN IRREGULAR COLONIES OR FILAMENTS; HIGHLY VARIABLE APPEARANCE

E1. CELLS RECTANGULAR, BRIGHT GREEN; JOINED INTO LONG FILAMENTS RADIATING FROM CENTRAL POINT TO FORM FLAT, SPHERICAL OR OVAL COLONY: Coleochaete

E2. CELLS SPHERICAL, WITH LONG, FLEXIBLE PSEUDOCILIA; LOOSELY ENCLOSED IN A CLUB-SHAPED COLONIAL MUCILAGE; EPIPHYTIC ON AQUATIC MACROPHYTES AND FILAMENTOUS ALGAE: Apiocystis

E3. CELLS SPHERICAL WITH SINGLE LONG, SHEATHED HAIR; SOLITARY OR IN IRREGULAR COLONIES OR FILAMENTS: Chaetosphaeridium

E4. CELLS HEMISPHERICAL (FLATTENED AGAINST SUBSTRATE), WITH LONG, BRANCHED HAIRS; SOLITARY OR IN IRREGULAR COLONIES OR FILAMENTS: Dicranochaete

D3. CELLS LACKING OR MOSTLY LACKING LONG HAIR-LIKE SETAE

C4. CELLS JOINED OR POSITIONED END-TO-END IN FILAMENTS OR PSEUDOFILAMENTS; FILAMENTS 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)