The Callistemon species have commonly been referred to as bottlebrushes because of their cylindrical, brush like flowers resembling a traditional bottle brush.
Flowering is normally in spring and early summer (October–December), but conditions may cause flowering at other times of the year. The obvious parts of the flower masses are stamens, with the pollen at the tip of the filament; the petals are inconspicuous (see picture). Flower heads vary in colour with species; most are red, but some are yellow, green, orange or white. Each flower head produces a profusion of triple-celled seed capsules around a stem which remain on the plant with the seeds enclosed until stimulated to open when the plant dies or fire causes the release of the seeds. A few species release the seeds annually.