Callistemon citrinus grows to between 1 and 3 metres in height and has leaves which are 3 to 7 cm long and 5 to 8 mm wide. The veins of the leaves are clearly visible on both sides. The flower spikes are 6 to 10 cm in length and about 4 to 7 cm in diameter. These appear in November and December (late spring to early summer) in the species native range. The stamens are red, purplish-red or lilac with dark-coloured anthers. The seed capsules are woody, cup-shaped and about 7mm wide and appear in clusters along the stems.
The species was formally described by English botanist William Curtis in the The Botanical Magazine in 1794, based on a flowering plant growing at Lord Cremorne's estate. This particular plant had been grown from a root sent from Botany Bay. Curtis classified this species within the genus Metrosideros, which had been erected by English botanist Joseph Banks in 1788. Curtis gave it the name Metrosideros citrina, noting that the leaves "when bruised give forth an agreeable fragrance". The species was transferred to the genus Callistemon in 1913 by botanist Homer Collar Skeels in the United States Department of Agriculture, Bureau of Plant Industry Bulletin. The species was known by the illegitimate name Callistemon lanceolatus for many years.
Distribution and habitat
It is native to the states of Queensland, New South Wales and Victoria in Australia, occurring in the vicinity of rocky streams and near-coastal swamps. In Victoria, the species occurs in the east of the state in association with tree species including Eucalyptus globoidea and E. consideniana.
Birds have been observed using the species as a source of food. Those seeking nectar from the flowers include Eastern Spinebills, New Holland Honeyeaters, Noisy Miners, Red Wattlebirds and Silvereyes, while Crimson Rosellas eat the seeds.
Callistemon citrinus had become established in cultivation in England by 1794 when flowering plants that were more than five years old had been observed at both Kew Gardens and Syon House and younger plants had become available in nurseries.
C. citrinus can be grown outdoors in warm, dry climates, with a minimum temperature of 7 °C (45 °F). It thrives in well-drained soils rich in organic matter, and direct sunlight. Indoors, it will grow well in normal room temperatures and low humidity. However, it requires more sunlight than most houseplants. Plants will benefit from being moved outdoors to a sunny area in summer. New plants can be grown by taking stem tip cuttings in spring or early summer. Cuttings can be rooted in a mix of peat moss and coarse sand, kept moist. Plants can also be sown by seed in spring.
Numerous cultivars have been selected including:
- 'Demesne Rowena' - A cross between 'Splendens' and 'White Anzac' growing to 1.5 x 1.5 metres. The flowers are red upon opening, fading to deep pink.
- 'Firebrand', a seedling of uncertain origin first planted at Austraflora Nursery in 1973. Plants are about 60 cm high and 2.5 metres wide and have deep crimson-pink flowers.
- 'Splendens', a form with a compact and rounded habit, growing to about 2 metres high and wide. It is sold under the trade name "Endeavour".
- 'White Anzac', a low, spreading white-flowering form selected from a natural population in New South Wales.
- Little John, aka Dwarf Bottlebrush. grows to 3' tall, 5' wide. Red flowers, blue-green leaves covering the branches. Drought-tolerant. (also classified as C.viminalis)
- Spencer, R.D.; Lumley P.F. "Callistemon citrinus (Curtis) Skeels". PlantNET - New South Wales Flora Online. Royal Botanic Gardens & Domain Trust, Sydney Australia. Retrieved 18 June 2012.
- Wild Plants of Victoria (database). Viridans Biological Databases & Department of Sustainability and Environment. 2009.
- "Metrosideros citrina". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government, Canberra. Retrieved 18 June 2012.
- Curtis, William. "Metrosideros citrina". The Botanical Magazine Vol. 8. Project Gutenberg. Retrieved 18 June 2012.
- "Metrosideros". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government, Canberra. Retrieved 18 June 2012.
- "Callistemon citrinus". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government, Canberra. Retrieved 18 June 2012.
- "Callistemon lanceolatus". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government, Canberra. Retrieved 18 June 2012.
- Lepschi, B.J. (1993). "Food of some birds in eastern New South Wales"Additions to Barker & Vestjens". Emu 93 (3): 195–199. doi:10.1071/MU9930195.
- "Bottle Brush Plant". Retrieved 2010-05-04.
- "List of Australian Registered Cultivars". Retrieved 2008-03-28.
- "Callistemon 'Demesne Rowena'". Descriptions of Registered Cultivars. Australian Cultivar Registration Authority. Retrieved 24 June 2012.
- "Callistemon 'White Anzac'". List of Registered Cultivars derived from Australian native flora. Retrieved 19 June 2012
- Derek Cornes (2005). "Callisto: a very successful maize herbicide inspired by allelochemistry". Fourth World Congress on Alleopathy. The Regional Institute Ltd. Retrieved 18 June 2012.