Casuarina equisetifolia

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Casuarina equisetifolia
Subspecies equisetifolia near Darwin
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Fagales
Family: Casuarinaceae
Genus: Casuarina
C. equisetifolia
Binomial name
Casuarina equisetifolia
  • C. e. subsp. equisetifolia
  • C. e. subsp. incana

Casuarina equisetifolia var. typica Domin

Subspecies incana near Rockhampton

Casuarina equisetifolia, commonly known as coastal she-oak, horsetail she-oak,[3] ironwood,[4] beach sheoak, beach casuarina or whistling tree[5] is a species of flowering plant in the family Casuarinaceae and is native to Australia, New Guinea, Southeast Asia and India. It is a small to medium-sized, monoecious tree with scaly or furrowed bark on older specimens, drooping branchlets, the leaves reduced to scales in whorls of 7 or 8, the fruit 10–24 mm (0.39–0.94 in) long containing winged seeds (samaras) 6–8 mm (0.24–0.31 in) long.


Casuarina equisetifolia is a monoecious tree that typically grows to a height of 6–12 m (20–39 ft), sometimes to 35 m (115 ft), and has bark that is smooth and greyish on young specimens, scaly or furrowed on older trees. The branchlets are drooping, up to 300 mm (12 in) long, the leaves reduced to scale-like teeth about 0.7 mm (0.028 in) long, arranged in whorls of 7 or 8 around the branchlets. The sections of branchlet between the leaf whorls (the "articles") are 5–13 mm (0.20–0.51 in) long and 0.5–1.0 mm (0.020–0.039 in) wide. Male flowers are arranged in spikes 7–40 mm (0.28–1.57 in) long in whorls of 7 to 11.5 per centimetre (per 0.39 in.) the anthers 0.6–0.8 mm (0.024–0.031 in) long. The female cones are on a peduncle 3–13 mm (0.12–0.51 in) long and sparsely covered with soft or woolly hairs. Mature cones are 10–24 mm (0.39–0.94 in) long and 9–13 mm (0.35–0.51 in) in diameter, the samaras 6–8 mm (0.24–0.31 in) long.[3][5][6]

Common names for the tree include Australian pine, horsetair tree, ironwood, beach sheoak; although it has features that seem superficially like a conifer, it is not a pine.[7]


The genus Casuarina was first formally described in 1759 by Carl Linnaeus in Amoenitates Academicae and the first species he described was Casuarina equisetifolia.[8][9] The specific epithet (equisetifolia) means "horsehair-leaved".[5]

In 1873, George Bentham described Casuarina equisetifolia var. incana and C. equisetifolia var. equisetifolia in Flora Australiensis.[10] and in 1982, Lawrie Johnson changed the names to subspecies equisetifolia and incana respectively, in the Journal of the Adelaide Botanic Gardens:[11]

  • Casuarina equisetifolia L. subsp. equisetifolia,[12] a tree 7–35 m (23–115 ft) high, the articles 5–8 mm (0.20–0.31 in) long and 0.5–0.7 mm (0.020–0.028 in) with 8 to 10 teeth 0.3–0.8 mm (0.012–0.031 in) long, the male spikes 7–40 mm (0.28–1.57 in) long, the cones 12–24 mm (0.47–0.94 in) long and 9–11 mm (0.35–0.43 in) wide on a peduncle 3–10 mm (0.12–0.39 in) long.[13]
  • Casuarina equisetifolia subsp. incana (Benth.) L.A.S.Johnson.[14] a tree 6–12 m (20–39 ft) high, the articles 7–13 mm (0.28–0.51 in) long and 0.7–1.0 mm (0.028–0.039 in) with 8 to 10 teeth about 0.7 mm (0.028 in) long, the male spikes 12–25 mm (0.47–0.98 in) long, the cones 10–20 mm (0.39–0.79 in) long, 10–13 mm (0.39–0.51 in) wide and densely covered with white to rust-coloured hairs, on a peduncle 3–13 mm (0.12–0.51 in) long.[3][15] The epithet incana means "white" or "hoary".[16]

There is some doubt as to whether Linnaeus' publication of C. equisetifolia is valid, since he based his description solely on Rumphius's description of Casuarina litorea in Herbarium Amboinense[17] and there are no type specimens.[18]

Distribution and habitat[edit]

Casuarina equisetifolia subsp. equisetifolia grows near the sea, behind beaches and near estuaries, sometimes on rocky headlands in Australia, New Guinea, Southeast Asia and India.[2][5] The species is native to India and Bangladesh in South Asia, Myanmar, the Andaman Islands, Nicobar Islands, Vietnam, Thailand, Cambodia, Peninsular Malaysia, the Philippines, Borneo, Java and the Lesser Sunda Islands, islands in the South China Sea, Sulawesi and Sumatra in Southeast Asia, the Carolines, Fiji, the Marianas, the Marshall Islands, New Caledonia, Samoa, Solomon Islands, Tonga, Tuvalu and Vanuatu in the Pacific Ocean, New Guinea, and New South Wales, the Northern Territory, and Queensland in Australia.[2][5][13]

Subspecies incana grows on rocky headlands near the coasts of eastern Queensland and New South Wales as far south as Laurieton.[3][5][15][19]

Casuarina equisetifolia has been introduced to many other continents and islands.[2] It is an invasive species in the United States, but biological control by insects, including by a Selitrichodes wasp and Carposinidae and Gelechiidae moths has been effective.[20][21][22] It is also regarded as being invasive in South Africa.[23]


Other than ornamental purposes, Casuarina was also explored in for its potential in remediation of textile dye wastewater. Casuarina leaves were found to be useful as absorbent material for the removal of textile dyes such as reactive orange 16[24] Rhodamine B,[25] methylene blue, malachite green[26] and methyl violet 2b.[27] Similarly the Casuarina dried cone was also reported to be able to remove Rhodamine B,[28] and methyl violet 2b.[29] The Casuarina bark was reported to able to remove methylene blue.[30] Even the Casuarina seed was also found to be useful in dye removal of neutral red and malachite green.[31] The carbon derived from the cones of Casuarina was found to be good absorbent for the landfill leachate,[32] while another laboratory also reported good absorbent for copper ions from aqueous solution.[33]


Names of places[edit]

In Singapore, there is a road named Tanjong Rhu Road because it once had many of these trees growing along the coast from Kallang to Rochor.[34] In the island of Langkawi, Kedah, Malaysia, there is a sand spit in the mouth of the Ayer Hangat river in the Kilim Karst Geoforest Park about 20 km from the town of Kuah also named Tanjung Rhu where these trees line here.[35] The town of Tanjung Aru in Sabah is also named because a lot of this tree (aru) is found in its beach.[36]

In the Philippines, the town of Agoo is named after the tree (known as agoho or aroo in the Ilocano language).[37]

Invasive species[edit]

Casuarina equisetifolia exhibits a high degree of adaptability to different environmental conditions, including coastal habitats, sandy soils, and disturbed areas. This versatility allows it to thrive in a wide range of ecosystems, increasing its potential for invasiveness.[38]

The species produces large quantities of winged seeds contained within cone-like structures. These seeds are easily dispersed by wind and water, facilitating the rapid spread of Casuarina equisetifolia over long distances. This dispersal mechanism enables it to colonize new areas and outcompete native species.[39]

Casuarina equisetifolia's lack of natural predators or pests contributes to its unchecked growth in many regions. While specific scientific references directly addressing this aspect might be limited, the absence of significant herbivory or predation on Casuarina equisetifolia in non-native environments has been observed in ecological studies documenting its invasive behavior [40][41]

Human activities such as urbanization, agriculture, and landscaping often contribute to the spread of Casuarina equisetifolia. The species is frequently planted for erosion control, windbreaks, and ornamental purposes, inadvertently introducing it to new areas where it can become invasive.[42]


See also[edit]


  1. ^ Barstow, M. (2019). "Casuarina equisetifolia". IUCN Red List of Threatened Species. 2019: e.T16728404A16728408. Retrieved 26 December 2023.
  2. ^ a b c d e "Casuarina equisetifolia". Plants of the World Online. Retrieved 29 April 2023.
  3. ^ a b c d Wilson, Karen L.; Johnson, Lawrence A.S. "Casuarina equisetifolia subsp. incana". Royal Botanic Garden Sydney. Retrieved 29 April 2023.
  4. ^ "Casuarina equisetifolia - Common Ironwood, Beach Sheoak, Horsetail Casuarina, Australian Pine, Australian Beefwood - Hawaiian Plants and Tropical Flowers". 2009-12-24. Retrieved 2023-10-27.
  5. ^ a b c d e f Boland, Douglas J.; Brooker, M. I. H.; Chippendale, G. M.; McDonald, Maurice William (2006). Forest trees of Australia. Collingwood, Victoria: CSIRO Publishing. p. 82. ISBN 0-643-06969-0.
  6. ^ "Casuarina equisetifolia". Australian Biological Resources Study, Department of Agriculture, Water and the Environment: Canberra. Retrieved 29 April 2023.
  7. ^ "Casuarina equisetifolia | Landscape Plants | Oregon State University". Retrieved 2023-10-28.
  8. ^ "Casuarina". APNI. Retrieved 21 April 2023.
  9. ^ Linnaeus, Carl (1759). Amoenitates academicae, seu, Dissertationes variae physicae, medicae, botanicae. p. 143. Retrieved 29 April 2023.
  10. ^ Bentham, George (1873). Flora Australiensis. Vol. 6. London: Lovell Reeve & Co. p. 197. Retrieved 29 April 2023.
  11. ^ Johnson, Lawrence A.S. (1982). "Notes on Casuarinaceae II". Journal of the Adelaide Botanic Gardens. 6 (1): 79. Retrieved 29 April 2023.
  12. ^ "Casuarina equisetifolia subsp. equisetifolia". Australian Plant Census. Retrieved 29 April 2023.
  13. ^ a b "Casuarina equisetifolia subsp. equisetifolia". Australian Biological Resources Study, Department of Agriculture, Water and the Environment: Canberra. Retrieved 29 April 2023.
  14. ^ "Casuarina equisetifolia subsp. incana". Australian Plant Census. Retrieved 29 April 2023.
  15. ^ a b "Casuarina equisetifolia subsp. incana". Australian Biological Resources Study, Department of Agriculture, Water and the Environment: Canberra. Retrieved 29 April 2023.
  16. ^ William T. Stearn (1992). Botanical Latin. History, grammar, syntax, terminology and vocabulary (4th ed.). Portland, Oregon: Timber Press. p. 431.
  17. ^ Rumphius, Georg E. (1743). Herbarium Amboinense. Vol. 3. Amsterdam. p. 86. Retrieved 29 April 2023.
  18. ^ Wilson, Karen L.; Johnson, Lawrence A.S. (1989). Flora of Australia (PDF). Canberra: Australian Government Publishing Service. p. 201. Retrieved 29 April 2023.
  19. ^ "Casuarina equisetifolia" (PDF). World Agroforestry (Centre for International Forestry Research). Retrieved 29 April 2023.
  20. ^ "Biological control of Australian native Casuarina species in the USA". Commonwealth Scientific and Industrial Research Organisation. 16 May 2007. Archived from the original on 5 June 2011. Retrieved 16 September 2010.
  21. ^ Masterson, J (4 October 2007). "Casuarina equisetifolia (Australian Pine)". Fort Pierce: Smithsonian Marine Station. Archived from the original on 2 July 2009. Retrieved 5 May 2009.
  22. ^ Purcell, Matthew. "Evaluating Biological Control Agents of Australian Pine". United States Department of Agriculture. Retrieved 30 April 2023.
  23. ^ "SANBI:Declared Weeds & Invader Plants". South African National Biodiversity Institute. Archived from the original on 2014-10-06. Retrieved 25 September 2014.
  24. ^ Bharti, Vikash; Shahi, Amrita; Geed, Sachin; Kureel, M.K. (2017). "Biodegradation of reactive orange 16 dye in the packed bed bioreactor using seeds of Ashoka and Casuarina as packing media". Indian Journal of Biotechnology. 16: 216–221.
  25. ^ Kooh, Muhammad Raziq Rahimi; Dahri, Muhammad Khairud; Lim, Linda B.L. (2016). "The removal of rhodamine B dye from aqueous solution using Casuarina equisetifolia needles as absorbent". Cogent Environmental Science. 2. doi:10.1080/23311843.2016.1140553.
  26. ^ Dahri, Muhammad Khairud; Kooh, Muhammad Raziq Rahimi; Lim, Linda B.L. (2015). "Application of Casuarina equisetifolia needle for the removal of methylene blue and malachite green dyes from aqueous solution". Alexandria Engineering Journal. 54 (4): 1253. doi:10.1016/j.aej.2015.07.005.
  27. ^ Dahri, Muhammad Khairud; Kooh, Muhammad Raziq Rahimi; Lim, Linda B. L. (2013). "Removal of Methyl Violet 2B from Aqueous Solution Using Casuarina equisetifolia Needle". ISRN Environmental Chemistry. 2013: 1–8. doi:10.1155/2013/619819.
  28. ^ Dahri, Muhammad Khairud; Kooh, Muhammad Raziq Rahimi; Lim, Linda B. L. (2016). "Remediation of Rhodamine B Dye from Aqueous Solution Using Casuarina equisetifolia Cone Powder as a Low-Cost Absorbent". Advances in Physical Chemistry. 2016: 1–7. doi:10.1155/2016/9497378.
  29. ^ "Water remediation using Casuarina equisetifolia cone as adsorbent for the removal of methyl violet 2B dye using batch experiment method". Journal of Environment & Biotechnology Research. 6 (1): 34–42. January 2017. Archived from the original on 19 March 2017 – via ViNaNiE.
  30. ^ "Adsorption of methylene blue by casuarina equisetifolia bark". Archived from the original on 2020-07-10. Retrieved 2018-02-15. {{cite journal}}: Cite journal requires |journal= (help)
  31. ^ "Application of microwave-treated Casuarina equisetifolia seeds in adsorption of dyes". Journal of Fundamental and Applied Sciences. 9: 458–471. 2017. doi:10.4314/JFAS.V9I7S.43 (inactive 31 January 2024). ISSN 1112-9867.{{cite journal}}: CS1 maint: DOI inactive as of January 2024 (link)
  32. ^ Alrozi, Rasyidah; Zubir, Nor Aida; Kamaruddin, Mohamad Anuar; Yusof, Siti Noor Faizah Mohd; Yusoff, Mohd Suffian (2017). "Removal of organic fractions from landfill leachate by Casuarina equisetifolia activated carbon: Characteristics and absorption mechanisms". AIP Conference Proceedings. 1885 (1): 020139. Bibcode:2017AIPC.1885b0139A. doi:10.1063/1.5002333.
  33. ^ Muslim, A. (2017). "AUSTRALIAN PINE CONES-BASED ACTIVATED CARBON FOR ADSORPTION OF COPPER IN AQUEOUS SOLUTION" (PDF). Journal of Engineering Science and Technology. 12 (2): 280–295.
  34. ^ Thulaja, Naidu Ratnala (24 January 2018) [31 December 2004]. "Tanjong Rhu Road". Infopedia. Government of Singapore. Retrieved 25 October 2022.
  35. ^ "Tanjung Rhu". Kilim Geoforest Park. The Cooperative of Kilim Village Community Langkawi Limited. 2022. Retrieved 25 October 2022.
  36. ^ "'Replant Aru trees, mangroves at Tanjung Aru blaze site' call". Daily Express. 22 July 2021. Retrieved 25 October 2022.
  37. ^ Sals, Florent Joseph (2005). The History of Agoo: 1578-2005. La Union: Limbagan Printhouse. p. 80.
  38. ^ Nandy, Paramesh; Ahammad, Ronju; Alam, Mesbahul; Islam, Aminul (2013), "Coastal Ecosystem Based Adaptation: Bangladesh Experience", Climate Change Adaptation Actions in Bangladesh, Tokyo: Springer Japan, pp. 277–303, doi:10.1007/978-4-431-54249-0_15, ISBN 978-4-431-54248-3, retrieved 2024-03-28
  39. ^ Zhang, Y.; Zhong, C.L.; Han, Q.; Jiang, Q.B.; Chen, Y.; Chen, Z.; Pinyopusarerk, K.; Bush, D. (2016). "Reproductive biology and breeding system in Casuarina equisetifolia (Casuarinaceae) – implication for genetic improvement". Australian Journal of Botany. 64 (2): 120. doi:10.1071/bt15184. ISSN 0067-1924.
  40. ^ Taylor, Mary (2021-01-26). "Plant growth regulators in crop management". doi:10.1079/hc.13880108.20219903029. Retrieved 2024-03-28.
  41. ^ Khare, C.P. (2007), "Casuarina equisetifolia Linn.", Indian Medicinal Plants, New York, NY: Springer New York, p. 1, doi:10.1007/978-0-387-70638-2_311, ISBN 978-0-387-70637-5, retrieved 2024-03-28
  42. ^ Kent, Eliza F. (2022-03-30), "Can Tamil Sacred Groves Survive Neoliberalism?", Sacred Forests of Asia, London: Routledge, pp. 102–103, doi:10.4324/9781003143680-10, ISBN 978-1-003-14368-0, retrieved 2024-03-28

External links[edit]