''Casuarina glauca'', commonly known as the swamp she-oak, swamp oak, grey oak, or river oak, is a species of ''

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 ...

'' native to the east coast of Australia. It is found from central Queensland south to southern New South Wales. It has become naturalised in the

Everglades The Everglades is a natural region of tropical climate, tropical wetlands in the southern portion of the U.S. state of Florida, comprising the southern half of a large drainage basin within the Neotropical realm. The system begins near Orland ...

in Florida where it is considered a weed.

Taxonomy

Franz Sieber Franz Wilhelm Sieber (30 March 1789 – 17 December 1844), was a botanist and collector who travelled to Europe, the Middle East, Southern Africa and Australia. Early life Franz Sieber was born in Prague, Bohemia on 30 March 1789. After 5&nb ...

described the swamp oak as ''Casuarina glauca'' in 1826. The species name is derived from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''glauca'' "glaucous". The Kabi name for the plant, ''bilai'', was used for the town and locality of

Bli Bli, Queensland Bli Bli () is a rural town and locality in the Sunshine Coast Region, Queensland, Australia. In the , Bli Bli had a population of 7,801 people. Geography A few kilometres inland from the Maroochydore urban area, Bli Bli rises above the wetlan ...

. The gadigal name is ''guman''. It is closely related to ''C. cunninghamiana''. Hybrids with ''C. cunninghamiana'' subsp. ''cunninghamiana'' have been recorded where the two species co-occur, such as at

Lower Portland Lower Portland is a rural suburb near Sydney, in the state of New South Wales, Australia. Lower Portland is located 80 kilometres northwest of the Sydney central business district, in the local government areas of The Hills Shire (east of t ...

and

Wisemans Ferry Wisemans Ferry is a cable ferry across the Hawkesbury River in New South Wales, Australia. The ferry operates from the eponymous community of Wisemans Ferry on the south bank, to a point on the north bank downstream of the Hawkesbury River's ...

Description

left, closeup of new growth, showing segmented branchlets with tiny brown teethlike leaves at nodes of segments 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 (7 ft) tall when exposed to the elements on clifftops. The greyish brown bark has scales and small fissures. 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. 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.

Distribution and habitat

''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. ''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.

Ecology

''C. glauca'' is an

actinorhizal plant Actinorhizal plants are a group of angiosperms characterized by their ability to form a symbiosis with the nitrogen fixing actinomycetota ''Frankia''. This association leads to the formation of nitrogen-fixing root nodules. Classification Actinor ...

producing root nitrogen-fixing nodules infested by ''

Frankia ''Frankia'' is a genus of nitrogen-fixing bacteria that live in symbiosis with actinorhizal plants, similar to the ''Rhizobium'' bacteria found in the root nodules of legumes in the family Fabaceae. ''Frankia'' also initiate the forming of root ...

''. There is a regular pattern of cell layers containing

flavan The flavans are benzopyran derivatives that use the 2-phenyl-3,4-dihydro-2''H''-chromene skeleton. They may be found in plants. These compounds include the flavan-3-ols, flavan-4-ols and flavan-3,4-diols (leucoanthocyanidin). A ''C''-glycosidic fl ...

s. Although not a legume, ''C. glauca'', produces a

hemoglobin Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythrocyte ...

(not a

leghemoglobin 3rd Leghemoglobin (also leghaemoglobin or legoglobin) is an oxygen-carrying phytoglobin found in the nitrogen-fixing root nodules of leguminous plants. It is produced by these plants in response to the roots being colonized by nitrogen-fixin ...

) 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''. ''Casuarina glauca'' 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 ''Juncus kraussii'' commonly known as salt marsh rush, sea rush, jointed rush, matting rush or dune slack rush, is of the monocot family Juncaceae and genus Juncus. It grows in salt marshes, estuarine and coastal areas. This species is ideal a ...

'', '' Baumea juncea'' and ''

Sporobolus virginicus ''Sporobolus virginicus'', known by numerous common names including seashore dropseed, marine couch, sand couch, salt couch grass, saltwater couch, coastal rat-tail grass, and nioaka, is a species of grass with a wide distribution. Description ...

'' on sandier soils and ''

Apium prostratum ''Apium prostratum'', commonly known as sea celery, is a variable herb native to coastal Australia and New Zealand. The leaves are variable, with toothed leaflets, and a celery like aroma. The tiny white flowers occur in clusters. There are tw ...

'', '' Carex appressa'', ''

Goodenia ovata ''Goodenia ovata'', commonly called the hop goodenia, is a species of flowering plant and is endemic to south-eastern Australia. It is a shrub with sticky, often varnished foliage, toothed egg-shaped to elliptic leaves and racemes or thyrses of ...

'', ''Juncus kraussii'' and ''

Phragmites australis ''Phragmites australis'', known as the common reed, is a species of plant. It is a broadly distributed wetland grass that can grow up to tall. Description ''Phragmites australis'' commonly forms extensive stands (known as reed beds), which may ...

'' and the vine ''

Parsonsia straminea ''Parsonsia straminea'', commonly known as common silkpod or monkey rope, is a woody vine of the dogbane family, Apocynaceae. It occurs in the states of New South Wales and Queensland in Australia. Taxonomy Prolific botanist Robert Brown collec ...

'' on clay soils.

Glossy black cockatoo The glossy black cockatoo (''Calyptorhynchus lathami''), is the smallest member of the subfamily Calyptorhynchinae found in eastern Australia. Adult glossy black cockatoos may reach in length. They are sexually dimorphic. Males are blackish br ...

s break the cones to eat the seeds, which mature in winter. The seed is eaten by the

red-browed finch The red-browed finch (''Neochmia temporalis'') is an estrildid finch that inhabits the east coast of Australia. This species has also been introduced to French Polynesia. It is commonly found in temperate forest and dry savannah habitats. It may ...

, and

peaceful dove The peaceful dove (''Geopelia placida'') is a pigeon native to Australia and New Guinea. The peaceful dove is closely related to the zebra dove of south-east Asia and the barred dove of eastern Indonesia. Until recently, the three were classed as ...

(''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 Ornamental plants or garden plants are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars that i ...

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 (50 ft) of the tree. It can also acidify acid sulphate soils as it lowers the water table. Casuarina glauca 'Cousin It'

Two prostrate forms are commercially available: ''Casuarina'' 'Cousin It' is a cultivar arising from material from

Booderee National Park Booderee National Park and Botanic Gardens, formerly Jervis Bay National Park and Jervis Bay Botanic Gardens, are located in the Jervis Bay Territory of Australia. The reserve is composed of two sections: * the Bherwerre Peninsula, on the souther ...

on the New South Wales south coast collected in 1989 and named for its resemblance to

Cousin Itt Cousin Itt is a fictional character in the ''Addams Family'' television and film series. He was developed specifically for the 1964 television series and is a regular supporting character in subsequent motion-picture, television and stage adaptat ...

, and ''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.

References

External links

{{Taxonbar, from=Q2941555 glauca Fagales of Australia Flora of New South Wales Flora of Queensland Trees of Australia Plants described in 1826