Anabaena - Fig 1 2, 3,  coiled filaments with intercalary heterocysts and akinetes.

Arthrospira - Fig. 1,  spiral filaments with transverse septations.

Cylindrospermum - Fig. 1  - filament similar to Anabaena but with single terminal heterocyst. If akinetes are present, they are adjacent to the heterocyst.

Coelosphaerium - Fig. 1, Cells occur in spherical or irregular colonies, with the cells occupying the peripheral portions of the matrix. Look for this genus in Wasserbluthe.

Croococcus - hemispherical cells in a common gelatinous matrix. Unicellular, or groups of 2 or 4.

Gloeocapsa - colonial spherical cells forming individual gelatinous envelopes within the common envelope of the mother cell.

Gloeotricha - Fig. 1, 2,3,  - tapering filament with a single terminal heterocyst and if present, and adjacent akinete, enclosed in a gelatinous sheath.

Lyngbya - Fig 1, 2  - similar to Oscillatoria, but with prominent sheath.

Merismopedia - Fig. 1, 2,3,  - flat colonies, one cell in thickness, arranged in transverse and vertical rows.

Microcystis - Fig. 1, 2, - spherical or irregular colonies with dense masses of cells in a gelatinous matrix. Cells occur throughout the matrix, contrasting with Coelosphaerium. This genus secrete toxins.

Nostoc - Fig. 1, 2, 3,  contorted filaments with intercalary heterocysts.  Filaments embedded in a firm gelatinous matrix. Form macroscopic gelatinous balls - see specimens.

Oscillatoria -Fig. 1. 2,3, 4, 5, 6, 7,  filaments of short cells, appearing to lack sheaths. Note the separation discs.

Rivularia - tapering trichomes, each having a single terminal heterocyst and NO akinete. Covered with sheath, especially at base of trichome. Often occur in clumps.

Scytonema - filaments with gelatinous sheaths. Demonstrate false branching, with the branches occurring in pairs.

Spirulina - Fig 1. 2, similar to Arthrospira, but with inapparent septations.

Stigonema - filaments showing true branching

Stromatolite  Fig. 1.

Tolypothryx - filaments surrounded by gelatinous sheath, and showing false branching. They have a single false branch arising beside a heterocyst.

Wasserbluthe - (Water bloom) - Fig 1, 2, 3, a mixture of floating blue-greens which often occur in great profusion when population explosions take place in lakes and ponds. May include Anabaena,Microcystis, and Coelosphaerium.

Mixtures: Fig 1,