Phylox series

The Phylox series was, according to the TARDIS information system, the planet on which the city of Castrovalva was located.

Exactly what was meant by the word series in an astronomical context was unknown. The Index File noted that "Castrovalva [was] the central habitation of the planet that forms the Phylox series". This begged the unanswered question of how a single object made a series.

However, the Index File was, at the time that Nyssa and Tegan consulted it about the Phylox Series, compromised. Because the Tremas Master instructed Adric to place this false entry into the Index File, the information was entirely suspect. The Phylox series may have never existed. (TV: Castrovalva)

The Phylox series might be synonymous with the Phylox system. (PROSE: Placebo Effect)