Sentient plant people native to the planet Phylos, the Phylosians of the twenty-third century are heirs to a civilization that is long past its prime — a civilization they wish to see restored to its former grandeur. Unfortunately, the Phylosians remember little that occurred before the advent of a plague that killed many of them off long ago.

By 2269, the Phylosians were being ruled by Dr. Stavos Keniclius 5, the fourth cloned copy of the original Eugenics Wars geneticist Dr. Stavos Keniclius from Earth. Under the direction of their indigenous leader Agmar, the Phylosians assisted Keniclius 5 in his efforts to create a genetically engineered master race ostensibly intended to "enforce? peace upon an unruly galaxy. After Captain Kirk and Commander Spock of the U.S.S. Enterprise dissuaded Keniclius 5 from this endeavor on stardate 5554.8 (2269), the Phylosians turned their energies toward rebuilding their culture, with the assistance of Keniclius 5 and a giant clone of Spock created by the geneticist.