Eucalyptus sideroxylon commonly known as Mugga, Red Ironbark or Mugga Ironbark, is a medium-sized to tall tree belonging to Family Myrtaceae. It is endemic to Australia and widely distributed in south-eastern Queensland, western slope and plains of New South Wales, and south  and central Victoria.

The tree has hard, deeply furrowed bark which is typical of ironbarks. The bark is persistent and deep brown to black in colour.

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A street tree of Eucalyptus sideroxylon in a Sydney suburb. The tree is about 15 m high.
Another street tree in a Sydney suburb
Another street tree of Eucalyptus sideroxylon in a Sydney suburb. This tree is about 18 m high.

Tree can grow up to about 35 m high. The smaller branches on the top may shed in short ribbons, exposing the white or grey colour under the bark.

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The bark of the tree trunk

Adult leaves are lanceolate in shape, 7–15 cm long, 1. 2–1.8 cm wide, green or grey-green in colour.

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Adult leaves are lanceolate in shape
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Leaf venation and oil glands in a fresh leaf viewed with transmitted light. The thicker yellow white structure is the midrib.
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Details of the above image

 

Eucalyptus sideroxylon starts flowering in mid autumn (March in Sydney). Flower buds are in group of 4 to 7 or more with long pedicles. The buds are ovoid in shape, 8 to 12 mm long, 4 to 6 mm in diameter. The operculum (bud cap) is conical, shorter and narrower than the hypanthium. The colour of the flowers is white or pink. The tree which I studied has beautiful pink flowers.

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    The flowers are arranged in an inflorescence of 4 to 7 or more. Each flower has long pedicel.
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    The development of the flower buds to flowers and finally to fruits

     

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    The operculum is still attached to the flower bud
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    After the removal of the operculum, parts of the stamens and the top part of the stigma are visible
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    The top view of the specimen above
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    The vertical section of the specimen above
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    The young stamens have been deliberately dislodged to show the anthers.
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    The appearance of the dislodged stamens of the other half of the flower bud
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    Mature stamens
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    Stigma with lots of pollen grains attached

     

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    The ovary is sagittally cut into halves to show the ovules inside.

     

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    Transverse section of the ovary showing 6 carpels inside
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    The ovules have been dislodged from the carpels to show the three dimensional appearance.

     

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    This flower possesses 7 carpels in its ovary

     

    Fruit is globose, hemispherical or ovoid, commonly 6-locular, 6–11 mm long, 5–9 mm diameter.

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    The appearance of the fruit of the previous year

     

    Eucalyptus sideroxylon produces dense, durable wood and has high resistance to rotting and termites. Its heartwood is dark red and the sapwood pale yellow. It has been used for a range of heavy duty applications including fencing, posts for transmission, piers, bridges, building timber, flooring, railway sleepers, beams and other engineering structures.

    The wood can be polished to a high sheen. It has been used for furniture, craftwood and benchtops. It can be used as fuelwood.

    The wood has a density of 1130 kg/m3 (1.3 g / cm3) It is one of the few timbers that will not float on water.

    The flowers produce nectar for honey production, pollen has value for apiculture (beekeeping)

    The leaves are used in the production of cineole based eucalyptus oil.

    Eucalyptus sideroxylon is suitable for medium to larger gardens and planted widely as street trees. It is hardy in a wide range of soils and climates. The tree is also frost tolerant.

     

    Acknowledgements

    I would like to thank Mr Andrew Orme of the National Herbarium of New South Wales (Royal Botanic Garden) for his help in identifying the tree.

     

    Bibliography

    https://en.wikipedia.org/wiki/Eucalyptus_sideroxylon

    https://www.florabank.org.au/lucid/key/Species%20Navigator/Media/Html/Eucalyptus_sideroxylon.htm

    http://anpsa.org.au/e-sider.html

     

     

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