Each chloroplast contains around 100 copies of its DNA in young leaves, declining to 15–20 copies in older leaves. They are usually packed into nucleoids which can contain several identical chloroplast DNA rings. Many nucleoids can be found in each chloroplast.
Though chloroplast DNA is not associated with true histones, in red algae, a histone-like chloroplast protein (HC) coded by the chloroplast DNA that tightly packs each chloroplast DNA ring into a nucleoid has been found.
In primitive red algae, the chloroplast DNA nucleoids are clustered in the center of a chloroplast, while in green plants and green algae, the nucleoids are dispersed throughout the stroma.