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

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

E1. CELLS RECTANGULAR, GOLDEN BROWN; FORMING IRREGULAR, RECTANGULAR COLONIES OR SHORT FILAMENTS; EPIPHYTIC ON FILAMENTOUS ALGAE: Phaeoplaca

E2. CELLS RECTANGULAR, BRIGHT GREEN; JOINED INTO LONG FILAMENTS RADIATING FROM CENTRAL POINT TO FORM FLAT, SPHERICAL OR OVAL COLONY: Coleochaete

E3. CELLS CLUB-SHAPED OR CYLINDRICAL; SOLITARY OR IN TREE-LIKE COLONIES WITH CELLS FORMING AT END OF ELONGATED PARENT CELL: Ophiocytium

E4. CELLS OVAL OR ELLIPTICAL AND BRIGHT BLUE-GREEN; SOLITARY OR IN SMALL COLONIES ENCLOSED IN OLD PARENT CELL WALL; OFTEN EPIPHYTIC: Glaucocystis

E5. LORICA SESSILE OR ATTACHED BY SHORT STIPE; CELLS TRUMPET-SHAPED OR CYLINDRICAL: Epipyxis

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)