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

D2. TRICHOMES WITH FALSE BRANCHING

E1. TRICHOMES TAPERED; FALSE BRANCHES HAVE ONE OR MORE HETEROCYSTS AT THE POINT OF BRANCH INITIATION; TRICHOMES ENCLOSED IN FIRM SHEATH: Dichothrix

E2. TRICHOMES NOT TAPERED; FALSE BRANCHING, WITH ONE OR MORE HETEROCYSTS AT THE BASE OF EACH BRANCH

E3. FALSE BRANCH DOES NOT HAVE HETEROCYSTS AT THE POINT OF BRANCH INITIATION: Scytonema

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)