Allocasuarina decaisneana
| Desert oak | |
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| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Rosids |
| Order: | Fagales |
| Family: | Casuarinaceae |
| Genus: | Allocasuarina |
| Species: | A. decaisneana |
| Binomial name | |
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Allocasuarina decaisneana L.A.S.Johnson |
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Allocasuarina decaisneana or desert oak is an attractive, 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.
The dioecious tree typically grows to a height of 10 to 16 metres (33 to 52 ft) and as high as 20 m (66 ft). and a width of 3 to 8 m (9.8 to 26.2 ft). Young trees have a narrow trunk and form< and grey/green feathery foliage. They mature to an adult form with spreading limbs and bushy foliage. It is the only member of its family in Central Australia and its large cylindrical cones are the biggest in its family.
The trees have a cork-like bark that is deeply furrowed and is known to protect the trees from fire.
Instead of leaves the tree has long segmented branchlets, known as cladodes, that resemble olive green pine needles. Each of the needles are composed of thin striped segments, which are leaf stalks, linked by a ring of projections, each of which is a tiny leaf. These perform the same function as leaves but conserve moisture. As the clalodes are shed from the tree they form a dense mat around the base preventing other plants from becoming established and competing for moisture and nutrients. The roots have nodules that contain nitrogen fixing bacteria, which allows them to survive in sandy soils with low nutrient levels. In the first few years, te slow growing tree develops a fast growing tap-root that can reach a depth of over 10 metres (33 ft) and can reach any sub-surface water.
Trees will bloom between March and June forming fluffy red or brown flowers that are small in size. These later form, the cylindrical seed cones that subsequently develop are up to 10 centimetres (4 in) in length, far larger than other Allocasuarine species.
Desert oaks can be propagated by seed, but they are not easy to grow outside of their natural environment.
Fire will burn the foliage but does not usually kill the tree. They are frost tolerant and drought tolerant.
Often found in swales between sand dunes they grow well in deep red sand. The species is distributed through the deserts of the eastern part of central Western Australia, in the southern portion of the Northern Territory, and in northern South Australia. It is often the only tree species to be found in these area where the dominant form of vegetation is spinifex.
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Wikipedia