The viridans streptococci are a large group of commensal streptococcal bacteria species that are either a-hemolytic, producing a green coloration on blood agar plates (hence the name "viridans", from Latin "viridis", green), or nonhemolytic. The pseudo-taxonomic term "Streptococcus viridans" is often used to refer to this group of species, but writers that do not like to use the pseudotaxonomic term (which treats a group of species as if they were one species) prefer the terms viridans streptococci, viridans group streptococci or viridans streptococcal species.