Hormogonia are motile filaments of cells formed by some cyanobacteria in the family Nostoceae. They're formed during asexual reproduction in unicellular, filamentous cyanobacteria some contain hetrocysts and akinetes. Cyanobacteria differentiate into hormogonia when exposed to an environmental stress or when placed in new media. Hormogonium differentiation's crucial for the development of nitrogen-fixing plant cyanobacteria symbioses, in particular that between cyanobacteria of the genus Nostoc… (More on Hormogonium)