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

D1. CELLS LENS-SHAPED AND COMPRESSED (L&<;W) WITH TRANSVERSE RING

E1. CELLS BRIGHT GREEN, SPHERICAL, WITH TRANSVERSE RING; FORMING UNISERIATE FILAMENTS (ONE CELL WIDE): Radiofilum

E2. CELLS BRIGHT GREEN, SPHERICAL, WITH TRANSVERSE RING; FORMING UNBRANCHED, UNISERIATE OR MULTISERIATE FILAMENTS OR PSEUDOFILAMENTS: Flintia

D2. CELLS CYLINDRICAL, MOSTLY LONGER THAN WIDE, WITH RIBBON-LIKE, BAND-LIKE, OR STAR-SHAPED CHLOROPLASTS

D3. CELLS VARIOUS SHAPES, INCLUDING CYLINDRICAL, BUT LACKING TRANSVERSE RINGS; CHLOROPLASTS NOT RIBBON-LIKE, BAND-LIKE, OR STAR-SHAPED; DIFFICULT GROUP WITH FEW OVERLAPPING FEATURES

C4. BRANCHED FILAMENTOUS ALGAE

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)