Basic colour: Various jewel-like colours - gold, copper, green, blue, violet, purple, magenta, sometimes black.
Pattern colour: None
Number of spots: None
Other colour forms: Many and common
Pronotoum: As basic colour
Leg colour: As basic colour
Confusion species: Plateumaris discolor
P. discolor may be a synonym of P. sericea, since P. sericea with smooth pronota intergrade with P. discolor with wrinkled pronota. For a discussion, see J. Bratton & M. Greenwood 1997. British reed beetles, Plateumaris and Donacia (Chrysomelidae): an identification aid using pronotum surface characters. Latissimus 8: 11-14. However, the Atlas of British and Irish species (Cox 2007), the latest checklist (Duff 2012) and the recent AIDGAP key (Hubble 2012) all consider them to be different species with intermediate forms.
Habitat: Various wetland habitats, generally less acidic sites than P. discolor (usually seen on aquatic vegetation).
Host plant: Various wetland plants, but adults most often seen on bur-reeds (Sparganium spp.).
Food: As larvae, probably at roots of various wetland plants. Adults found on flower heads, so may be pollen-feeders, at least in part.
Other notes: Separation from P. discolor may require dissection of males to investigate the aedeagus.