Eucalyptus erythrocorys or red-cap Gum - (Illyarrie ) is a mallee from Western Australia. It is a small tree, 3-10m tall and can be very ornamentail in a garden. The bark is smooth but can have a few rough patches where it persists on the trunk instead of being shed. The Illyarrie is notable for its big flowers which can be 5 cm across or more. They are bright yellow, being covered by a bright-red cap (operculum) in bud - giving the epithet erythrocorys (red-helmet).