The kingdom monera only exists in the five-kingdom system. Monerans were put into kingdom plantae in the two-kingdom system, and into protista in the three-kingdom system. Putting monerans into a separate kingdom was very useful because monerans aren't quite protists, and aren't like plants at all.
Members of the kingdom monera have the following characteristics:
Prokaryotic
Unicellular
Some monerans are anaerobic, others are aerobic
Some are heterotrophic, others are autotrophic
Autotrophic monerans either utilize photosynthesis or chemosynthesis
They live in moist environments
The monera kingdom can be split into two kingdoms, eubacteria and archaebacteria, creating a six-kindom system.