Flagship of the Emerald Chain and command ship of its leader Osyraa in the 32nd century.
The Viridian was the flagship of the Emerald Chain, the criminal syndicate that dominated much of the galaxy in the decades after the Burn, and served as the command ship of its leader Osyraa.
After Osyraa seized Discovery, the Viridian staged a pretended pursuit in There Is a Tide... as Discovery approached Federation Headquarters. The ruse was meant to hide from Admiral Vance the fact that the Emerald Chain had taken control of the Starfleet ship.