Freshwater Algae Key

A1. NONMOTILE ALGAE WITHOUT CHLOROPLASTS: CYANOBACTERIA

B1. VEGETATIVE CELLS USUALLY SOLITARY

B2. VEGETATIVE CELLS UNITED INTO COLONIES

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

C1. CELLS ARE JOINED END-TO-END TO FORM TRICHOMES; TRICHOMES CONTAIN HETEROCYSTS

C2. CELLS ARE JOINED END-TO-END TO FORM TRICHOMES; TRICHOMES DO NOT CONTAIN HETEROCYSTS

D1. TRICHOMES ARE ATTACHED TO AQUATIC PLANTS (EPIPHYTIC) OR ASSOCIATED WITH ZOOPLANKTON MUCILAGE (ENDOGLOEIC)

E1. TRICHOMES VERY SHORT (<10 CELLS), EMBEDDED IN ROTIFER OR ALGAE MUCILAGE (ENDOGLOEIC): Pseudanabaena

E2. SOLITARY ELONGATED BASAL CELL ENCLOSED IN AN OPEN ENDED SHEATH, USUALLY WITH ONE OR MORE EXOCYTES (SPORE-LIKE REPRODUCTIVE CELLS): Chamaesiphon

E3. SOLITARY SHORT BASAL CELL ENCLOSED IN AN OPEN ENDED SHEATH, USUALLY WITH NUMEROUS EXOCYTES (SPORE-LIKE REPRODUCTIVE CELLS): Stichosiphon

E4. SOLITARY ELONGATED BASAL CELL (NOT IN SHEATH), USUALLY WITH ONE OR MORE EXOCYTES (SPORE-LIKE REPRODUCTIVE CELLS): Cyanophanon

E5. SOLITARY SHORT, CLUB-SHAPED BASAL CELL, WITH ONLY ONE EXOCYTE (SPORE-LIKE REPRODUCTIVE CELLS): Geitleribactron

D2. TRICHOMES ARE NOT EPIPHYTIC OR ENDOGLOEIC

C3. CELLS FORM PSEUDOFILAMENTS WHERE INDIVIDUAL CELLS ARE ALIGNED END-TO-END BUT NOT JOINED ACROSS THE END WALL

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)