Casuarina glauca (scaly oak (Australia))
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Plant Type
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Biology and Ecology
- Latitude/Altitude Ranges
- Air Temperature
- Rainfall Regime
- Soil Tolerances
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Impact Summary
- Environmental Impact
- Impact: Biodiversity
- Social Impact
- Risk and Impact Factors
- Wood Products
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Casuarina glauca Sieber ex Spreng.
Preferred Common Name
- scaly oak (Australia)
International Common Names
- English: black casuarina (Australia); black she-oak (Australia); Brazilian oak (Australia); gray she-oak (Australia); grey buloke; grey she-oak (Australia); longleaf casuarina; scaly bark beefwood (Australia); suckering Australian pine; suckering casuarina (Australia); swamp oak (Australia); swamp she-oak (Australia)
- Spanish: casuarina; pino de Australia
- French: pin d'Australie
Local Common Names
- Bahamas: suckerling Australian pine
- Malaysia: ru paya
- CSUGL (Casuarina glauca)
- swamp she-oak
Summary of InvasivenessTop of page Binggeli (1999) considered this to be a highly invasive tree species. It is now a category 1 pest plant species in Florida, USA where its distribution is being monitored (Miller et al., 2002). It is considered a category 1 invasive plant species in the Bahamas (BEST Commission, 2003). Smith (1998) considered it to be the most invasive of the Casuarinas on the Hawaiian islands. Like other invasive Casuarinas it is able to take advantage of disturbed sites for colonization.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Dicotyledonae
- Order: Casuarinales
- Family: Casuarinaceae
- Genus: Casuarina
- Species: Casuarina glauca
Notes on Taxonomy and NomenclatureTop of page The casuarinas are a group of 96 species of trees and shrubs which comprise the family Casuarinaceae (Wilson and Johnson, 1989). They have been placed in four genera: Allocasuarina, Casuarina, Ceuthostoma and Gymnostoma. A useful summary of the taxonomy, distribution and genetic variation in casuarinas is provided by Turnbull (1990). The genus Casuarina comprises 11 tree species, including 4 species with two subspecies each (Boland et al., 1996), although narrower species circumscriptions recognize up to 17 species. They are mostly endemic to Australia, but with some representation in South-East Asia and the Pacific Islands.
The generic name is from the Latin 'casuarius' (a cassowary), likening the pendulous branchlets to the drooping feathers of the cassowary. The specific name is drawn from the Greek 'glaukos' which is a descriptive term for the blue-green (glaucous) leaves, and the common name 'she-oak' relates to the patterning of the wood, comparable to but less strong than oak (World Agroforestry Centre, 2002).
DescriptionTop of page C. glauca is a medium-sized tree 8-20 m high, often with buttressed and fluted stem; rarely a shrub to about 2 m that frequently regenerates through vigorous root suckers. Branchlets spreading or drooping, to 38 cm long. Bark hard, grey or grey-brown, finely fissured and scaly, with a tessellated appearance. Leaves 8-20 mm long and 0.9-1.2 mm in diameter, glabrous; leaf-teeth in whorls of 12-17, rarely 20, erect, 0.6-0.9 mm long. Leaf-teeth on new shoots long and recurved. Male flowers, clusters with pollen along 1.2-4 cm of the tips of some branchlets 7-10 whorls per cm. Rounded female 'cones' are 3-12 mm on stalked heads, hairy when young, reddish- to white-pubescent, becoming glabrous, about 6 mm, with dark red stigmas. Mature woody cones subglobose to shortly cylindrical, 9-18 x 7-9 mm, bracteoles broadly acute, opening to release one pale, winged nutlet 3.5-5 mm long (WAC, 2005).
Plant TypeTop of page Perennial
DistributionTop of page C. glauca originates from the south-eastern coast of Australia (Elfers, 1988). C. glauca's natural habitat in Australia is river estuaries, where it is often very conspicuous. Native range habitats include estuarine floodplains, salt marshes, estuarine floodplains, saline swamp flats, sand dunes and the edges of mangroves (Elfers, 1988; WAC, 2005; Weber, 2003). In its native Australia, C. glauca may occur with Melaleuca quinquenervia and Eucalyptus robusta. In the successional process it is usually replaced by C. cunninghamiana (Elfers, 1988).
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Planted||Reference||Notes|
|Israel||Present||Introduced||Weinstein, 1993; WAC, 2005|
|South Africa||Present||Introduced||Planted||WAC, 2005|
|-Florida||Present||Introduced||Invasive||Planted||Miller et al., 2002|
|-Hawaii||Present||Introduced||Invasive||Smith, 1998; Weber, 2003|
Central America and Caribbean
|Antigua and Barbuda||Present||Introduced||Planted|
|Bahamas||Present||Introduced||Invasive||Hammerton, 2001; BEST Commission, 2003|
|Cuba||Present||Introduced||Invasive||Oviedo Prieto et al., 2012|
|Dominican Republic||Present||Introduced||WAC, 2005|
|Puerto Rico||Present||Introduced||WAC, 2005|
|Saint Vincent and the Grenadines||Present||Introduced||Planted|
|American Samoa||Present||Introduced||PIER, 2002|
|-Australian Northern Territory||Present||Introduced||Planted|
|-New South Wales||Present||Native||Planted, Natural|
|New Zealand||Present||Introduced||Planted||Bulloch, 1994|
|Norfolk Island||Present||Introduced||PIER, 2002|
|Papua New Guinea||Present||Introduced||Planted|
History of Introduction and SpreadTop of page C. glauca has been introduced to many countries as a timber, fuel and fodder tree, and for soil conservation. It was introduced to Florida, USA before 1924 and planted extensively for shelter and amenity (Anon., 1997). Elfers (1988) relates that it was originally introduced to the same habitats as C. equisetifolia in Florida, but was found less able to tolerate salt-spray and saline soils. Smith (1998) reports it to be widespread across the Hawaiian islands, where it is an aggressive colonizer. Outside its natural range Weber (2003) states that it invades sandy banks and beaches, and Hammerton (2001) reports that it can colonize disturbed sites.
Risk of IntroductionTop of page This species is classified as potentially invasive by Binggeli (1999) and is registered as invasive in Florida, Bahamas and Hawaii. Other species within its genus (e.g. C. equisetifolia, C. cunninghamiana) are also invasive and have been a source of serious environmental problems. The wide introduction of this species across many tropical and subtropical countries may constitute a risk for future invasive events.
Habitat ListTop of page
|Coastal areas||Present, no further details||Harmful (pest or invasive)|
Biology and EcologyTop of page Genetics
Closely related species are C. equisetifolia and C. cunninghamiana, and these Casuarinas readily interbreed forming hybrids. C. glauca and C. cunninghamiana are particularly closely related and hybrids are quite common in cultivation (El-Lakhany et al., 1990). Significant inter- and intra-provenance variation in survival and growth has been found. The chromosome number of C. glauca is 2n=18 (World Agroforestry Centre, 2002).
Physiology and Phenology
WAC (2005) notes that C. glauca is able to form monospecific stands in open woods and is moderately fast-growing. It is less tolerant of saline soils and salt-spray than the related C. equisetifolia (Elfers, 1988). C. glauca fixes atmospheric nitrogen through actinorhizal associations with Frankia spp. in root nodules (Hammerton, 2001), which facilitates its colonization of poor soils (Anon., 1997). Hammerton (2001) claims that C. glauca is among the most fire-sensitive of Casuarina spp., and that it also suffers when grazed. C. glauca is sensitive to fire (Weber, 2003). C. glauca can be grown using the same silvicultural practices as C. equisetifolia and C. cunninghamiana. Methods suitable for propagating casuarinas from seed are described by Carter (1987), Doran (1990) and Doran and Turnbull (1997). Bai and Zhong (1996) briefly describe methods used in China.
The flowers are dioecious. C. glauca is probably wind-pollinated but insect pollination can also occur. Seed production is prolific with approximately 414,900 seeds/kg (WAC, 2005). The seeds are winged samaras. In storage, seeds can survive for many years (WAC, 2005). In The Bahamas, it is able to produce flowers and fruit all year-round (Hammerton, 2001). C. glauca regularly produces root suckers and coppices readily, and root suckers may even be formed by undamaged trees (Elfers, 1988). Where root suckering is left unchecked, inpenetrable thickets may result (Hammerton, 2001). In Florida, USA spread is thought to be through root suckers as it is not known to produce seed there (Anon., 1997).
C. glauca is suited to warm humid and subhumid climatic zones, and although it will tolerate absolute minimum temperatures as low as 4°C, it is sensitive to heavy frosts. C. glauca tolerates a wide range of adverse conditions, including periodic waterlogging, drought, salt spray and highly saline soils, but is less tolerant of saline soils and salt-spray than the related C. equisetifolia (Elfers, 1988). It is generally a low altitude, coastal species, though may be planted at higher elevations.
In its native Australia, C. glauca may occur with Melaleuca quinquenervia and Eucalyptus robusta. In the successional process it usually precedes C. cunninghamiana by which it is replaced (Elfers, 1988). C. glauca forms actinorhizal associations with Frankia spp. in root nodules. This allows nitrogen fixation to occur (Hammerton, 2001).
Latitude/Altitude RangesTop of page
|Latitude North (°N)||Latitude South (°S)||Altitude Lower (m)||Altitude Upper (m)|
Air TemperatureTop of page
|Parameter||Lower limit||Upper limit|
|Absolute minimum temperature (ºC)||-4|
|Mean annual temperature (ºC)||13||24|
|Mean maximum temperature of hottest month (ºC)||25||33|
|Mean minimum temperature of coldest month (ºC)||2||15|
RainfallTop of page
|Parameter||Lower limit||Upper limit||Description|
|Dry season duration||0||7||number of consecutive months with <40 mm rainfall|
|Mean annual rainfall||570||2180||mm; lower/upper limits|
Rainfall RegimeTop of page Bimodal
Soil TolerancesTop of page
- seasonally waterlogged
Special soil tolerances
Notes on Natural EnemiesTop of page Pests include several pathogens such as Casuarina bacterial wilt, Pseudomonas solanacearum affecting the roots, herbivores including wood-boring Coleoptera such as Stromatium fulvum, the larvae of which burrow through the inner bark, sapwood and heartwood. Another wood borer, Macrotoma palmata (Coleoptera) is known to attack C. glauca in Egypt. Termites including Kalotermes flavicollis (in Egypt), Microtermes michaelseni and Ancistrotermes latinotus (both in Zimbabwe) are known to increase mortality (World Agroforestry Centre, 2002).
Means of Movement and DispersalTop of page Seeds (samaras) are wind dispersed (Weber, 2003). The related species C. cunninghamiana and equisetifolia are also known to achieve some dispersal by water. In Australia, the fruits of all species of Casuarina are a major food source for several species of parrots (Schodde et al., 1993) though no information was available on whether these birds disperse the seeds. Referring to Casuarina species in general, Snyder (1992) states that seeds may be transported by animals.
Impact SummaryTop of page
|Fisheries / aquaculture||None|
ImpactTop of page Elfers (1988) reports that the vigorous root system damages pavements, lawns and blocks and fractures sewer and water pipes. Falling trees can be dangerous in hurricanes and damage property (Elfers, 1988). The control of Casuarina is costly. Invasive Casuarinas are reported to increase soil erosion (e.g. Elfers, 1988; Hammerton, 2001).
Environmental ImpactTop of page Invasive Casuarina specie including C. glauca are reported to increase soil erosion (e.g. Elfers, 1988; Hammerton, 2001).
Impact: BiodiversityTop of page Like other invasive Casuarina species, C. glauca is capable of forming dense monospecific stands that, through shading and deposition of litter, shroud out the native understorey flora (Weber, 2003). Habitat changes caused by invasion of various Casuarina species, constitute a risk to loggerhead turtles, green sea turtles, the gopher tortoise and many small mammals (see Elfers, 1988).
Social ImpactTop of page The dense thickets formed by this species can make areas inaccessible. Casuarina pollen can be allergenic and act as a respiratory irritant (Elfers, 1988).
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Highly adaptable to different environments
- Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
- Highly mobile locally
- Has high reproductive potential
- Has propagules that can remain viable for more than one year
- Damaged ecosystem services
- Ecosystem change/ habitat alteration
- Negatively impacts human health
- Reduced native biodiversity
- Highly likely to be transported internationally deliberately
- Difficult to identify/detect in the field
- Difficult/costly to control
UsesTop of page C. glauca has been widely planted to revegetate disturbed soils and to reclaim land especially in coastal environments. The species has been planted to reduce erosion and conserve soil. It has also been used for shelter and windbreaks, and as a hedge plant. C. glauca has been planted as an ornamental and amenity tree in coastal locations. It can improve soil fertility because of its nitrogen-fixing ability. It produces excellent fuelwood which can be used to produce a high-quality charcoal (WAC, 2005). The timber is used for posts, piles, building timbers, light construction, flooring, fences, industrial and domestic woodware, tool handles and carvings. Wood fibre can be used to make particleboard (WAC, 2005). Leaves can be used as fodder for cattle, goats and sheep, and as an ingredient in chicken feed (WAC, 2005).
Wood ProductsTop of page
Sawn or hewn building timbers
- Exterior fittings
- For light construction
- Industrial and domestic woodware
- Tool handles
Similarities to Other Species/ConditionsTop of page Closely related species are C. equisetifolia and C. cunninghamiana, and these Casuarinas readily interbreed forming hybrids. C. glauca and C. cunninghamiana are particularly closely related and hybrids are quite common in cultivation (El-Lakhany et al., 1990).
Prevention and ControlTop of page Hammerton (2001) claims that C. glauca is among the most fire-sensitive of the Casuarinas, and that it also suffers when grazed. Fires have been used to control the related Casuarina equisetifolia when trees occur in high density and the location permits (Weber, 2003). In relation to the Casuarinas as a group, Elfers (1988) specified that disturbance of natural habitats should be minimized to reduce opportunities for colonization and where habitats had to be disturbed, swift replanting with indigenous vegetation was recommended. An alternative cultural approach was to counteract potential invasion by periodic flooding (Elfers, 1988). Weber (2003) reports that adults of the related species C. equisetifolia can be killed by spraying with triclopyr applied to a band at the bottom of the stem. Summarizing control information for the Casuarina spp. as a group (i.e. C. cunninghamiana, C. equisetifolia and C. glauca), Elfers (1988) noted that common methods of control are basal bark injection or cut stump application of triclopyr. Manual removal is feasible for saplings and seedlings (Weber, 2003).
ReferencesTop of page
Anon., 1997. Casuarina glauca sieber ex spreng. University of Florida, USA: Center for Aquatic and Invasive Plants. http://aquat1.ifas.ufl.edu/casgla.pdf.
Bai J; Zhong C, 1996. Management of casuarina plantations in China. In: Pinyopusarerk K, Turnbull JW, Midgley SJ, eds. Recent Casuarina Research and Development. Proceedings of the 3rd International Casuarina Workshop, Da Nang, Vietnam. Canberra, Australia: CSIRO Forestry and Forest Products, 196-200.
BEST Commission, 2003. Invasive plant species. Bahamas Environment, Science and Technology (BEST) Commission. http://www.best.bs/Invasive_plant_species.htm.
Binggeli P, 1999. Invasive woody plants. http://members.lycos.co.uk/WoodyPlantEcology/invasive/index.html.
Boland DJ; Brooker MIH; Chippendale GM; Hall N; Hyland BPM; Johnston RD; Kleinig DA; Turner JD, 1984. Forest trees of Australia. 4th ed. Melbourne, Australia:Thomas Nelson and CSIRO. xvi + 687 pp.; 77 ref.
Carter EJ, 1987. From Seed to Trial Establishment. DFR User Series No. 2. Canberra, Australia: CSIRO Forestry and Forest Products.
Cremer KW, 1990. Trees for rural Australia. Melbourne, Australia: Inkata Press.
Doran JC, 1990. Nursery practice. In: Cremer KW, ed. Trees for Rural Australia. Melbourne, Australia: Inkata Press, 89-106.
Doran JC; Turnbull JW, 1997. Australian trees and shrubs: species for land rehabilitation and farm planting in the tropics. Australian trees and shrubs: species for land rehabilitation and farm planting in the tropics., viii + 384 pp.; [refs].
El Lakany MH, 1983. A review of breeding drought resistant Casuarina for shelterbelt establishment in arid regions with special reference to Egypt. Forest Ecology and Management, 6(2):129-137; 49 ref.
Elfers SC, 1988. Element Stewardship Abstract for Casuarina equisetifolia Australian Pine. The Nature Conservancy, Arlington, Virginia, USA. http://tncweeds.ucdavis.edu/esadocs/documnts/casuequ.html.
El-Lakany MH; Mohamed SY, 1993. Root characteristics of four tree species as affected by irrigation systems. Alexandria Journal of Agricultural Research, 38:183-210.
El-Lakany MH; Omran TA; Shehata MS, 1990. Effects of the season of seed collection and storage temperature on seed germinability and subsequent seedling growth of casuarina species grown in Egypt. In: El-Lakany MH, Turnbull JW, Brewbaker JL, eds. Advances in Casuarina Research and Utilization. Proceedings of the 2nd International Casuarina Workshop. Cairo, Egypt: Desert Development Centre.
El-Lakany MH; Omran TA; Shehata MS, 1990a. Effects of the season of seed collection and storage temperature on seed germinability and subsequent seedling growth of casuarina species grown in Egypt. In: El-Lakany MH, Turnbull JW, Brewbaker JL, eds. Advances in Casuarina Research and Utilization. Proceedings of the 2nd International Casuarina Workshop. Cairo, Egypt: Desert Development Center, 188-194.
El-Lakany MH; Turnbull JW; Brewbaker JL, eds. , 1990. Advances in Casuarina Research and Utilization. Proceedings of the 2nd International Casuarina Workshop. Cairo, Egypt: Desert Development Centre.
El-Osta MLM; El-Morshedy MM; Megahed MM, 1996. Properties of particleboard from casuarina and willow mixtures. Bulletin of Faculty of Agriculture, University of Cairo, 47:129-140.
Faridah Hanum I; Maesen LJG van der, eds. , 1997. Plant resources of southeast Asia. No. 11. Auxillary plants. Leiden, Netherlands: Backhuys.
Hammerton JL, 2001. Casuarinas: a clear and present danger. Bahamas Journal of Science, 9, 2-14.
Hoy NT; Gale MJ; Walsh KB, 1994. Revegetation of a scalded saline discharge zone in central Queensland. 1. Selection of tree species and evaluation of an establishment technique. Australian Journal of Experimental Agriculture, 34(6):765-776; 24 ref.
Midgley SJ; Turnbull JW; Johnson RD eds, 1983. Casuarina Ecology, Management and Utilization. Proceedings of the 1st International Casuarina Workshop. Melbourne, Australia: CSIRO.
Miller JH; Chambliss EB; Bargeron CT, 2002. Invasive Plants of the Thirteen Southern States. http://www.invasive.org/seweeds.cfm.
Oviedo Prieto R; Herrera Oliver P; Caluff MG, et al. , 2012. National list of invasive and potentially invasive plants in the Republic of Cuba - 2011. (Lista nacional de especies de plantas invasoras y potencialmente invasoras en la República de Cuba - 2011). Bissea: Boletín sobre Conservación de Plantas del Jardín Botánico Nacional de Cuba, 6(Special Issue 1):22-96.
Pal M; Bakshi M; Bhandari HCS, 1994. Rooting cladode segments: a new technique for the rapid mass clonal propagation of cladode bearing plant species. Indian Forester, 120:729-732.
PIER, 2002. Pacific Island Ecosystems at Risk (PIER) (3.3). Institute of Pacific Islands Forestry, Hawaii, USA. http://www.hear.org/pier
Pinyopusarerk K; Turnbull JW; Midgley SJ; eds, 1996. Recent Casuarina Research and Development. Proceedings of the 3rd International Casuarina Workshop, Da Nang, Vietnam. Canberra, Australia: CSIRO Forestry and Forest Products.
Pryor LD, 1989. Vegetative propagation of Casuarina and Acacia: potential for success. In: Boland DJ, ed. Trees for the tropics. ACIAR Monograph No. 10, 155-157.
Redden P. Bowen GD, Robson AD, 1986. Nodulation of Casuarinaceae in relation to host species and soil properties. Australian Journal of Botany, 34:435-444.
Schodde R; Mason IJ; Wood JT, 1993. Geographical differentiation in the glossy black-cockatoo Calyptorhynchus lathami (Temminck) and its history. Emu, 93:156-166.
Smith CW, 1998. Pest Plants of Hawaiian Native Ecosystems. University of Hawaii, USA: Department of Botany. http://www.botany.hawaii.edu/faculty/cw_smith/aliens.htm.
Snyder SA, 1992. Casuarina spp. In: Fire Effects Information System, (online), U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Services Laboratory. http://www.fs.fed.us/database/feis/plants/tree/casspp/introductory.html.
WAC, 2005. Agroforestree database. World Agroforestry Centre: Nairobi, Kenya. http://www.worldagroforestry.org/Sites/TreeDBS/AFT/AFT.htm.
Wilson KL; Johnson LAS, 1989. Casuarinaceae. Flora of Australia, 3:100-189.
World Agroforestry Centre, 2002. Agroforestree Database. Nairobi, Kenya: ICRAF. http://www.worldagroforestrycentre.org/Sites/TreeDBS/AFT/AFT.htm.
Distribution MapsTop of page
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