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

D1. TRICHOMES UNBRANCHED, LACKING BOTH FALSE AND TRUE BRANCHING; MAY BE STRAIGHT, CURVED, OR TWISTED

E1. TRICHOMES ENCLOSED IN RUBBERY MUCILAGE FORMING SPHERICAL OR OVAL COLONIES; MICROSCOPIC OR MACROSCOPIC COLONIES: Nostoc

E2. TRICHOMES WITH HETEROCYSTS AT ONE OR BOTH ENDS (BASAL HETEROCYSTS)

E3. TRICHOMES WITH INTERCALARY HETEROCYSTS (HETEROCYSTS SCATTERED ALONG TRICHOME)

D2. TRICHOMES WITH FALSE BRANCHING

D3. TRICHOMES FORM TRUE BRANCHES; TRICHOMES MAY BE UNISERIATE (ONE CELL WIDE) OR MULTISERIATE (TWO OR MORE CELLS WIDE)

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

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)