Eucalyptus sideroxylon

Red Ironbark, Mugga Ironbark

Family: Myrtaceae

An ironbark eucalypt, potentially reaching 35 m high, though much shorter in cultivation.

Eucalyptus sideroxoxylon is found in open forest and woodland, mainly on the tablelands, western slopes and plains of New South Wales, although it also occurs on the fringes of the Sydney basin, extending into Queensland and Victoria (through the inland parts).

The bark is that of an ironbark and very dark in colour.

Juvenile leaves are dull grey-green or glaucous.

Adult leaves are lanceolate, to about 15 cm long, and about 2 cm wide, green or grey-green.

Eucalypts produce flowers in an umbellaster, an umbel-like cluster which can have 3, 7, 11-15 or more flowers. They are 7-flowered in this species. Umbellasters will be produced in the leaf axils.

Flowers can be white, to creamy yellow, to a rich pink or even red, which makes it a very appealing tree.

The capsules are cup-shaped with a long pedicel (which allows for easy identification within the ironbark group).

They are very hardy, needing less than 400 mm of rain per year to survive, yet can grow in climates with more than 1000 mm of rain per year.

In the garden

It is tolerant of frosts, droughts and poor soil.

It is an attractive tree for parks or large gardens, with dark bark, grey leaves and attractive flowers, especially if red. It is reasonably slow growing.

Flowering occurs from April to December and the flowers are white, red, pink or creamy yellow and are attractive to nectar eating birds.

The author has observed that this tree is suited to growing on heavy clay soils and performs well in Sydney’s north.

Street trees can be found through Sydney.


Propagation is from seed which germinates readily. Because of the genetic variation that occurs with seedlings, the red and pink flowered forms cannot be guaranteed to come true to type but usually do.

Other information

The wood is relatively hard and dense, and is often used for firewood. It has very high resistance to rotting and can be used for fence posts, piers, sleepers.
It can regenerate from seed, lignotuber and epicormic buds after fire.

Eucalyptus sideroxylon is one of the best known of the Ironbarks. There are two subspecies recognised:
– subsp. sideroxylon is the common form found over most of the range of the species (although with only has a very slight incursion into Victoria)
– subsp. tricarpa is found along the south coast of New South Wales, the north-east coast of Victoria and in central Victoria. The latter differs from subsp. sideroxylon in having fewer flowers in its inflorescence, larger buds and fruit and broader juvenile foliage.

It has become invasive in southern Africa.

Eucalyptus – from Greek, eu, “well” or “true” and calyptus, referring to the calyptra (καλύπτρo) or operculum, which is a bud cap or covering which covers the developing flowers. The calyptra is a fusion of petals and/or sepals and is shed when the flower opens.

sideroxylon – from the Greek sidero (σίδερο) – iron; and xylon (ξύλο) – wood, referring to the very strong wood.

Not considered to be at risk in the wild.



By Jeff Howes