''Allocasuarina'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of trees in the

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

family

Casuarinaceae The Casuarinaceae are a family of dicotyledonous flowering plants placed in the order Fagales, consisting of four genera and 91 species of trees and shrubs native to eastern Africa, Australia, Southeast Asia, Malesia, Papuasia, and the Pacifi ...

. They are

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

, occurring primarily in the south. Like the closely related genus ''

Casuarina ''Casuarina'' is a genus of 17 tree species in the family Casuarinaceae, native to Australia, the Indian subcontinent, southeast Asia, islands of the western Pacific Ocean, and eastern Africa. It was once treated as the sole genus in the fami ...

'', they are commonly called sheoaks or she-oaks. Wilson and Johnson distinguish the two very closely related genera, ''

'' and ''Allocasuarina'' on the basis of:
*''

'': the mature samaras being grey or yellow-brown, and dull; cone bracteoles thinly woody, prominent, extending well beyond cone body, with no dorsal protuberance; *''Allocasuarina'': the mature samaras being red-brown to black, and shiny; cone bracteoles thickly woody and convex, mostly extending only slightly beyond cone body, and usually with a separate angular, divided or spiny dorsal protuberance.

Description

They are trees or shrubs that are notable for their long, segmented branchlets that function as leaves. Formally termed cladodes, these branchlets somewhat resemble

pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accep ...

needles, although sheoaks are

s. The

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

are reduced to minute scales encircling each joint. Fallen cladodes form a dense, soft mat beneath sheoaks, preventing the development of undergrowth (a phenomenon known as

allelopathy Allelopathy is a biological phenomenon by which an organism produces one or more biochemicals that influence the germination, growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have be ...

) and making sheoak woods remarkably quiet. Another characteristic feature are the spiny "cones", about the size of an acorn but with a texture more resembling a

conifer cone A conifer cone (in formal botany, botanical usage: strobilus, plural strobili) is a seed-bearing organ on gymnosperm plants. It is usually woody, ovoid to globular, including scales and bracts arranged around a central axis, especially in con ...

. However, sheoak "cones" are a woody

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

. As with

legume A legume () is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Legumes are grown agriculturally, primarily for human consumption, for livestock f ...

s, sheoak roots possess nodules containing

symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...

nitrogen fixing Nitrogen fixation is a chemical process by which molecular nitrogen (), with a strong triple covalent bond, in the air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. Atmo ...

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

; together with their highly

drought A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...

-adapted foliage, this enables sheoaks to thrive in very poor soil and semi-arid areas. However, sheoaks are much less

bushfire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire ...

-tolerant than

eucalypt Eucalypt is a descriptive name for woody plants with capsule fruiting bodies belonging to seven closely related genera (of the tribe Eucalypteae) found across Australasia: ''Eucalyptus'', ''Corymbia'', ''Angophora'', '' Stockwellia'', ''Allosyn ...

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s of closely related species have been found dating back to the time of

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...

Uses

The hard wood and rich texture makes sheoak wood popular among

wood-turners Woodturning is the craft of using a wood lathe with hand-held tools to cut a shape that is symmetrical around the axis of rotation. Like the potter's wheel, the wood lathe is a simple mechanism that can generate a variety of forms. The operator ...

. Sheoak wood is also regarded as an excellent firewood as it burns with very little ash. Because of its ability to grow and develop extensive root systems in very poor or sandy soils, and to completely cover the ground with its "needles", it is often used to stabilise soils in

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

prone areas, or on sand dunes. Sheoak is also used as an ornamental shrub, although for this purpose the mat of "needles" may become a nuisance and must be carefully considered.

List of species

''Allocasuarina'' comprises the following species: * '' Allocasuarina acuaria'' * '' Allocasuarina acutivalvis'' * '' Allocasuarina brachystachya'' * ''

Allocasuarina campestris ''Allocasuarina campestris'', commonly known as the Shrubby she-oak, is a shrub of the she-oak family Casuarinaceae native to Western Australia. The dioecious or monoecious shrub typically grows to a height of and produces red-brown flowers fro ...

'' (tamma) * '' Allocasuarina corniculata'' * ''

Allocasuarina crassa ''Allocasuarina crassa'', commonly known as Cape Pillar sheoak, is a species of flowering plant in the family Casuarinaceae and is endemic to a small area in far south-eastern Tasmania. It is a low shrub to small tree that is monoecious or di ...

'' (Cape Pillar sheoak) * ''

Allocasuarina decaisneana ''Allocasuarina decaisneana'' or desert oak is a medium-sized, slow-growing tree found in the dry desert regions of the Northern Territory, South Australia and Western Australia. The Anangu peoples know the tree as kurkara. Description Th ...

'' (Desert oak) * ''

Allocasuarina decussata ''Allocasuarina decussata'', commonly known as karri oak or karri she-oak, is a medium-sized tree, or more rarely a shrub, that is endemic to the south west of Western Australia. It is an understory tree in karri forest but also occurs as a stun ...

'' (Karri oak) * '' Allocasuarina defungens'' * '' Allocasuarina dielsiana'' (Northern sheoak) * '' Allocasuarina diminuta'' * ''

Allocasuarina distyla ''Allocasuarina distyla'', commonly known as scrub she-oak, is a shrub or small tree of the She-oak family Casuarinaceae endemic to New South Wales. Description This dioecious shrub or small tree will typically grow to a height of tall, or 7 me ...

'' (Scrub sheoak) * '' Allocasuarina drummondiana'' * '' Allocasuarina duncanii'' (Duncan's sheoak) * '' Allocasuarina emuina'' (Emu Mountain sheoak) * '' Allocasuarina eriochlamys'' * '' Allocasuarina fibrosa'' (Woolly sheoak) * '' Allocasuarina filidens'' (Mount Beerwah sheoak) * ''

Allocasuarina fraseriana ''Allocasuarina fraseriana'', commonly known as western sheoak, common sheoak, WA sheoak. Fraser's sheoak or just sheoak, is a tree in the family Casuarinaceae. Endemic to Western Australia, it occurs near the coast in the south west corner o ...

'' (Western sheoak) * ''

Allocasuarina glareicola ''Allocasuarina glareicola'' is a species of flowering plant in the family Casuarinaceae and is endemic to a restricted part of New South Wales. It is an erect, dioecious or monoecious shrub that has branchlets up to long, the leaves reduced to ...

'' * '' Allocasuarina globosa'' * '' Allocasuarina grampiana'' * '' Allocasuarina grevilleoides'' * '' Allocasuarina gymnanthera'' * '' Allocasuarina helmsii'' * '' Allocasuarina huegeliana'' (Rock sheoak) * '' Allocasuarina humilis'' (Dwarf sheoak) * '' Allocasuarina hystricosa'' Wege * ''

Allocasuarina inophloia ''Allocasuarina inophloia'', also known as woolly oak, or stringybark she-oak, is a shrub or small tree of the she-oak family Casuarinaceae endemic to inland New South Wales and Queensland. The hairy bark is an unusual feature. Taxonomy First co ...

'' (Hairy oak) * '' Allocasuarina lehmanniana'' (Dune sheoak) * ''

Allocasuarina littoralis ''Allocasuarina littoralis'', commonly known as black sheoak, black she-oak, or river black-oak, is an endemic medium-sized Australian tree (usually up to 8 metres, but sometimes to 15 metres - coarse shrub in exposed maritime areas). A. littoral ...

'' (Black sheoak) * ''

Allocasuarina luehmannii ''Allocasuarina luehmannii'' (buloke or bull-oak) is a species of ironwood tree native to Australia and its wood is the hardest commercially available as measured by the Janka Hardness Scale. Description The evergreen tree typically grows ...

'' (Bull-oak or buloke) * '' Allocasuarina mackliniana'' (Western sheoak) * '' Allocasuarina media'' * ''

Allocasuarina microstachya ''Allocasuarina microstachya'' is a species of flowering plant in the family Casuarinaceae and is endemic to the south-west of Western Australia. It is dioecious shrub that has its leaves reduced to scales in whorls of four, the mature fruiting c ...

'' * '' Allocasuarina misera'' * '' Allocasuarina monilifera'' * ''

Allocasuarina muelleriana ''Allocasuarina muelleriana'', commonly known as the slaty sheoak, is a small tree of the genus ''Allocasuarina'' native to South Australia and Victoria. The fast growing dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a spec ...

'' (Slaty sheoak) * ''

Allocasuarina nana ''Allocasuarina nana'', commonly known as dwarf she-oak or as stunted sheoak, is a species of flowering plant in the family Casuarinaceae and is endemic to south-eastern continental Australia. It is a low, spreading dioecious, rarely monoecious ...

'' * '' Allocasuarina ophiolitica'' * '' Allocasuarina paludosa'' (Scrub sheoak) * '' Allocasuarina paradoxa'' * '' Allocasuarina pinaster'' * ''

Allocasuarina portuensis ''Allocasuarina portuensis'', commonly known as the Nielsen Park she-oak, is an extremely rare plant growing in Sydney, Australia. Encountered as a shrub or small slender tree, up to tall, it has green drooping branchlets up to in length. It ...

'' * '' Allocasuarina pusilla'' (Dwarf sheoak) * '' Allocasuarina ramosissima'' * '' Allocasuarina rigida'' * '' Allocasuarina robusta'' * '' Allocasuarina rupicola'' * '' Allocasuarina scleroclada'' * '' Allocasuarina simulans'' * '' Allocasuarina spinosissima'' * '' Allocasuarina striata'' (Small bull-oak) * '' Allocasuarina tessellata'' * '' Allocasuarina thalassoscopica'' * '' Allocasuarina thuyoides'' (Horned she-oak) * '' Allocasuarina tortiramula'' (Twisted sheoak) * ''

Allocasuarina torulosa ''Allocasuarina torulosa'', the rose she-oak or forest oak, is a tree which grows in sub-rainforest (just outside the main forest area) of Queensland and New South Wales, Australia. There, it is typically found on coastal footslopes, hills, and ...

'' (Forest sheoak) * '' Allocasuarina trichodon'' * ''

Allocasuarina verticillata ''Allocasuarina verticillata'', commonly known as drooping she-oak or drooping sheoak, is a nitrogen fixing native tree of southeastern Australia. Originally collected in Tasmania and described as ''Casuarina verticillata'' by French naturalist ...

'' (Drooping sheoak)Allocasuarina verticillata
Windmill Outback Nursery, 2003-03-13. Retrieved 2007-01-23. * '' Allocasuarina zephyrea''

Species names with uncertain taxonomic status

The status of the following species is unresolved: * ''Allocasuarina decemilinanana''

References

External links

* *
Research team
fro
IRD
working on

{{Taxonbar, from=Q135346 Fagales genera Fagales of Australia