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)

D2. TRICHOMES ARE NOT EPIPHYTIC OR ENDOGLOEIC

E1. TRICHOMES ARE SPIRALLING OR COILED AND USUALLY HIGHLY MOTILE: Arthrospira and Spirulina

E2. MULTIPLE TRICHOMES ENCLOSED IN A WIDE, COMMON MUCILAGE: Microcoleus

E3. CELLS VERY SHORT RELATIVE TO WIDTH (COIN-LIKE); TRICHOMES WIDE AND MOSTLY UNTAPERED (MAY HAVE SLIGHTLY TAPERED TERMINAL CELL)

E4. CELLS CUBICAL, CYLINDRICAL, OR OVAL; ISODIAMETRIC (L=W), OR SLIGHTLY SHORTER OR LONGER THAN WIDTH (NOT COIN-LIKE)

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)