Callistemon or Bottlebrush are evergreen shrubs originating from Australia. The flower spikes of bottlebrushes form in spring and summer and are made up of a number of individual flowers. The pollen from these flowers forms on the tip of a long coloured stalk called a filament. The filaments are usually yellow or red. Leaves of many bottlebrushes are very ornamental. The leaves are often coloured and, in some species, they are covered with fine, soft hairs. Callistemon grow well in most soils but do not tolerate highly alkaline soil. They can be dead-headed after flowering; this will encourage new season growth.