Casuarina glauca
Swamp She-oak
Swamp She-oak
Wikipedia links: Angiosperms > Eudicots > Rosids > Fagales > Casuarinaceae > Casuarina glauca
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Common name: Swamp She-oak
Also, swamp oak, grey oak, or river oak
The Kabi name for the plant, bilai, was used for the town and locality of Bli Bli, Queensland
The gadigal name is guman
Conservation status: unknown
Etymology:
Flowers:
Fruit:
Leaves:
The leaves themselves are reduced to tiny 'teeth' that are 0.6 to 0.9 mm long. 12–17 (rarely 20) teeth arise from the nodes between articles on the branchlets
The oval cones are 9–18 mm long by 7–9 mm wide
Stem & branches:
The swamp oak grows as medium sized tree, 8–20 m high tree, or rarely over 30 m tall
It can be restricted to a stunted shrub around 2 m tall when exposed to the elements on clifftops
The greyish brown bark has scales and small fissure
The branches have numerous drooping branchlets that are up to 38 cm long and composed of small cylindrical segments known as articles
These articles are 8 to 20 mm long and 0.9–1.2 mm wide
Roots:
Habit:
Habitat:
Casuarina glauca grows in or near brackish water along the banks of rivers and estuaries
Suckering from the roots, the swamp oak can form dense stands of trees
It grows on alluvial soils of sandstone or shale origin
The water table lies 30 cm or less under the surface
This tree then acts to turn shallows into land by preventing erosion and collecting material among its roots
Distribution:
Native to the east coast of Australia
Casuarina glauca is found along Australia's east coast from Yeppoon in central Queensland to Bermagui in southern New South Wales
Some stands within the Royal Botanic Gardens in Sydney predate European settlement
Populations along the New South Wales coastline are at risk due to clearing of habitat for development
It has become highly invasive in Florida
It is found from central Queensland south to southern New South Wales. It has become naturalised in the Everglades in Florida where it is considered a weed
Additional notes:
Taxonomy
Franz Sieber described the swamp oak as Casuarina glauca in 1826.[3] The species name is derived from the Latin glauca "glaucous"
It is closely related to C. cunninghamiana.[8] Hybrids with C. cunninghamiana subsp. cunninghamiana have been recorded where the two species co-occur,[7] such as at Lower Portland and Wisemans Ferry
Ecology
C. glauca is an actinorhizal plant producing root nitrogen-fixing nodules infested by Frankia
There is a regular pattern of cell layers containing flavans.[12] Although not a legume, C. glauca, produces a hemoglobin (not a leghemoglobin) in its symbiotic root nodules
The rat's tail orchid (Dendrobium teretifolium) grows on the swamp oak
The larvae of the she-oak moth, Pernattia pusilla, feed on C. glauca
Can trees can live to 100 to 200 years
Trees regenerate after fire by growing from the roots. Cut stumps sprout suckers vigorously, producing groves of new trees
Casuarina glauca trees drop large amounts of litter, mainly old cones and branchlets, which eventually rots down and enriches the soil unless removed by a flood event
Understory plants recorded from swamp oak groves include Juncus kraussii, Baumea juncea and Sporobolus virginicus on sandier soils and Apium prostratum, Carex appressa, Goodenia ovata, Juncus kraussii and Phragmites australis and the vine Parsonsia straminea on clay soils
Glossy black cockatoos break the cones to eat the seeds, which mature in winter
The seed is eaten by the red-browed finch, and peaceful dove (Geopelia placida)
Cultivation and uses
Casuarina glauca has been planted widely as a street tree in Canberra
It was introduced to Haiti to stabilise the soil and to be used as timber for poles, and to Florida where it was planted as an ornamental plant and windbreak
The bark has been used to plant orchids on
It tolerates waterlogged soils and even soils with some salinity
A significant inconvenience in urban settings is that its roots can invade underground water and sewer pipes if these are within 15 m of the tree
It can also acidify acid sulphate soils as it lowers the water table
'Cousin It' cultivar
Two prostrate forms are commercially available: Casuarina 'Cousin It' is a cultivar arising from material from Booderee National Park on the New South Wales south coast collected in 1989 and named for its resemblance to Cousin Itt
C. ‘Kattang Karpet’ is propagated by the Australian Botanic Garden from material collected at Kattang Nature Reserve on the New South Wales mid-north coast in 1998
Sources of information: