Abstract: To explore its life history characteristics, solid culture of hormogoniumand regular sampling and production, morphological changes were studied during the development of hormogoniumunder microscope. The results showed that the life history of the hormog-oniumwas composed of four stages: hormogonium, the minimal colonies, filamentation of seriate colonies and the different diameter colonies. The vegetative proliferation of the emerald green Nostocsphaeroideswas mainly caused by hormogoniumand germinal repro-duction. In addition, the heterocystdifferentiation was promoted by the number of algal cells, and it was related to the formation of ‘embryonic bud’ of germinal reproduction and the fracture of single algae filaments between groups in the later stage of budding. The results showed that hormogoniumwas the key targets of growth and differentiation regulation. In the process of seed production of Nostocsphaeroides, it is necessary to pay attention to the effect of heterocyston the regulation of growth and differentiation of Nostocsphae-roides.

Key words: Nostocsphaeroides, life history characteristics;hormogonium, germinal reproduction