A rosella is one of five to eight species of colorful Australian parrots in the genus Platycercus.
Platycercus means "broad-tailed" or "flat-tailed", reflecting a feature common to the rosellas and other members of the broad-tailed parrot tribe.
Their diet is mainly seeds and fruit.
Early European settlers encountered the Eastern Rosella at Rose Hill, New South Wales, now Parramatta, and so they called it the Rosehill Parakeet, which became, "Rosehiller", and eventually "Rosella".
Ranging in size from 26 to 37 cm (10 to 14.5 in), rosellas are medium-sized parrots with long tails.
The feathers on their backs show an obvious scalloping appearance with colouring that differs between the species.
All species have distinctive cheek patches.
Sexual dimorphism is absent or slight - males and females generally have similar plumage, apart from the Western Rosella.
The juveniles of the blue-cheeked species, and Western Rosella, all have a distinctive green-based plumage, while immature plumage of the white-cheeked species is merely a duller version of the adults.