Pseudobranches (‘false’ branches) lack any change in the plane of cell division.  They are formed in one of two ways, resulting in a connection breakage and separation of any pair of adjacent cells in the trichome.  Also an extracellular sheath (mucilage matrix) must be present to hold the resulting two trichome fragments together.  Depending on which way they are formed, the pseudobranches will be paired or singular:

1.  Paired pseudobranches:  A ‘rigid’ sheath may be tightly attached to the cells that produce it, thus preventing movement or gliding of cells along the sheath.  When intercalary (‘in between the ends of the trichome) cell division and elongation occurs, the trichome bends or ‘buckles’ forming a bulge.  Continued divison and elongation enlarges the bulge, eventually resulting in a fracture.  The pair of pseudobranches can continue to elongate.

2.  Singular pseudobranches:  Where heterocysts are present (Nostocales) and a cell adjacent a heterocyst divides, it can form a single pseudobranch by severing from the heterocyst and continuing cell division and growth.   A common example is Scytonema.

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