Casuarina

Description

Plants in the genus Casuarina are dioecious trees (apart from C. equisetifolia that is monoecious), with fissured or scaly greyish-brown to black bark. They have soft, pendulous, green, photosynthetic branchlets, the leaves reduced to scale-like leaves arranged in whorls of 5 to 20 around the branchlets. The branchlets are segmented at each whorl with deep furrows that conceal the stomates. Male flowers are arranged along branchlets in spikes with persistent bracteoles, female flowers in spikes on short side-branches (effectively "peduncles") that differ in appearance from vegetative branchlets. After fertilisation, the female spikes develop into "cones" with thin, woody bracteoles that extend well beyond the cone body. The cones enclose grey or yellowish-brown winged seed known as samaras.

Ecology

Casuarina are attacked by a range of herbivorous insects.

• Hymenoptera: The wasps Bootanelleus orientalis and another Bootanelleus species (Torymidae) feed on seeds. Selitrichodes casuarinae and S. utilis (Eulophidae) induce galls.
• Lepidoptera: Most lepidopteran herbivores are in the family Oecophoridae. Zauclophora pelodes, Araeostoma aenicta and Lichenaula sp. feed on leaves, and the latter two are also leaf tiers. Cryptophasa irrorata bores in branches and stems. Outside of Oecophoridae, there are fruit- and leaf-feeders in families Carposinidae and Gelechiidae.
• Curculionidae: A weevil in genus Haplonyx feeds on cones. The genera Misophrice and Apion have also been recorded on Casuarina, but the nature of their associations is unknown.
• Hemiptera: Casuarinicola jumping plant lice (Triozidae) feed on sap of Casuarina. Another hemipteran associated with this genus is the felt scale Choneochiton casuarinae (Eriococcidae).
• Diptera: The gall midge Ophelmodiplosis clavata (Cecidomyiidae) induces galls on branchlet tips.

Taxonomy

The genus Casuarina was first formally described in 1759 by Carl Linnaeus in Amoenitates Academicae and the first species he described (the type species) was Casuarina equisetifolia. The generic name is derived from the Malay word for the cassowary, kasuari, alluding to the similarities between the bird's feathers and the plant's foliage.

Species List

The following is a list of Casuarina species accepted by Plants of the World Online as of April 2023:

• Casuarina collina Poiss. ex Pancher & Sebert (New Caledonia)
• Casuarina cristata Miq. – belah, muurrgu (Qld., N.S.W.).
• Casuarina cunninghamiana Miq. – river oak, river sheoak, creek oak (Qld., N.S.W., A.C.T., N.T.)
• Casuarina equisetifolia L. – coastal she-oak, horsetail she-oak (South Asia, Southeast Asia, Australia)
• Casuarina glauca Sieber ex Spreng. – swamp she-oak, swamp buloke, marsh sheoak (Qld., N.S.W.)
• Casuarina grandis L.A.S.Johnson (New Guinea)
• Casuarina junghuhniana Miq. (Indonesia)
• Casuarina obesa Miq. – swamp she-oak, swamp oak, western swamp oak (W.A., S.A., Vic., N.S.W.)
• Casuarina oligodon L.A.S.Johnson (New Guinea)
• Casuarina orophila L.A.S.Johnson (New Guinea)
• Casuarina pauper F.Muell. ex L.A.S.Johnson – black oak, belah, kariku (W.A., S.A., Qld., N.S.W., Vic.)
• Casuarina potamophila Schltr. (New Caledonia)
• Casuarina tenella Schltr. (New Caledonia)
• Casuarina teres Schltr. (New Caledonia)

In 1982, Lawrence Johnson raised the genera Allocasuarina and Gymnostoma in the Journal of the Adelaide Botanic Gardens, and transferred some species previously included in Casuarina to the new genera. The species of Allocasuarina previously in Casuarina are: A. acuaria, A. acutivalvis, A. campestris, A. corniculata, A. decaisneana, A. decussata, A. dielsiana, A. distyla, A. drummondiana, A. drummondiana, A. fraseriana, A. grevilleoides, A. helmsii, A. huegeliana, A. humilis, A. inophloia, A. lehmanniana subsp. lehmanniana, A. littoralis, A. luehmannii, A. microstachya, A. monilifera, A. muelleriana, A. nana, A. paludosa, A. paradoxa, A. pinaster, A. pusilla, A. ramosissima, A. rigida, A. robusta, A. striata, A. tessellata, A. thuyoides, A. torulosa, A. trichodon and A. verticillata. The species of Gymnostoma previously included in Casuarina are G. chamaecyparis, G. deplancheanum, G. intermedium, G. leucodon, G. nobile, G. nodiflorum, G. papuanum, G. poissonianum, G. rumphianum and G. sumatranum and G. webbianum.

Invasive species

C. cunninghamiana, C. glauca and C. equisetifolia have become naturalized in many countries, including Argentina, Bermuda, Cayman Islands, Cuba, China, Egypt, Israel, Iraq, Mauritius, Kenya, Mexico, Brazil, South Africa, the Bahamas, and Uruguay. They are considered an invasive species in the United States, especially in southern Florida where they have nearly quadrupled in number between 1993 and 2005 and are called the Australian pine. C. equisetifolia is widespread in the Hawaiian Islands where it grows both on the seashore in dry, salty, calcareous soils and up in the mountains in high rainfall areas on volcanic soils. It is also an invasive plant in Bermuda, where it was introduced to replace the Juniperus bermudiana windbreaks killed by a scale insect in the 1940s.

References

References

1. "''Casuarina''". Plants of the World Online.
2. "FIELD GUIDE TO IDENTIFY THE COMMON CASUARINA (AUSTRALIAN PINE) SPECIES IN FLORIDA". [[University of Florida]].
3. "''Casuarina glauca'' prostrate forms". Australian National Biodiversity Research.
4. "''Casuarina''". Australian Biological Resources Study, Department of Climate Change, the Environment and Water: Canberra.
5. {{FloraBase
6. "Genus ''Casuarina''". Royal Botanic Garden Sydney.
7. "''Casuarina''". Royal Botanic Gardens Victoria.
8. "''Casuarina''". Northern Territory Government.
9. (1992). "New RHS Dictionary of Gardening". [[Macmillan Publishers]].
10. Wheeler, G. S.. (2011-05-01). "Ecology and Management of Sheoak (Casuarina spp.), an Invader of Coastal Florida, U.S.A.". Journal of Coastal Research.
11. (2014-04-23). "Two new species of Selitrichodes (Hymenoptera: Eulophidae: Tetrastichinae) inducing galls on Casuarina (Casuarinaceae)". Zootaxa.
12. "Evaluating Biological Control Agents of Australian Pine : USDA ARS".
13. (2010-09-02). "Casuarinicola, a new genus of jumping plant lice (Hemiptera: Triozidae) from Casuarina (Casuarinaceae)". Zootaxa.
14. (2014-03-05). "A new genus and species of felt scale (Hemiptera: Coccoidea: Eriococcidae) from New Caledonia". Zootaxa.
15. (2012). "A new genus and species of gall midge (Diptera: Cecidomyiidae) from Casuarina trees in Australia: New gall midge from Casuarina". Australian Journal of Entomology.
16. "''Casuarina''". APNI.
17. (1759). "Amoenitates academicae, seu, Dissertationes variae physicae, medicae, botanicae".
18. Quattrocchi, Umberto. (2000). "CRC World Dictionary of Plant Names". CRC Press.
19. Govaerts R. "''Casuarina'' L.". Board of Trustees of the Royal Botanic Gardens, Kew.
20. (1982). "Note on Casuarinaceae II". Journal of the Adelaide Botanic Gardens.
21. BEST Commission. (March 2003). "The National Invasive Species Strategy for The Bahamas". BEST.
22. USFS FEIS: [http://www.fs.fed.us/database/feis/plants/tree/casspp/all.html ''Casuarina'']
23. USDA Forest service: [http://www.na.fs.fed.us/pubs/silvics_manual/volume_2/casuarina/casaurina.htm ''Casuarina''] {{Webarchive. link. (2013-02-11)
24. "GISD".
25. "Casuarina (''Casuarina equisetifolia'')". Government of Bermuda.