''Eucalyptus microtheca'', commonly known as the coolibah, is a species of tree that is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to northern Australia. It has rough, flaky or fibrous bark on the trunk and branches, lance-shaped adult leaves, flower buds in groups of seven, white flowers and spherical to conical fruit. It is widely distributed from the Kimberley region of Western Australia to Cape York in Queensland.

Description

''Eucalyptus microtheca'' is a tree, sometimes a mallee, that typically grows to a height of and forms a

lignotuber A lignotuber is a woody swelling of the root crown possessed by some plants as a protection against destruction of the plant stem, such as by fire. Other woody plants may develop basal burls as a similar survival strategy, often as a response t ...

. It has a whitish grey to dark grey, box-type bark that is often deeply fissured, coarsely flaky or tessellated as it ages. Young plants and

coppice Coppicing is a traditional method of woodland management which exploits the capacity of many species of trees to put out new shoots from their stump or roots if cut down. In a coppiced wood, which is called a copse, young tree stems are repeate ...

regrowth have narrow lance-shaped leaves that are long, wide and petiolate. Adult plants have leaves that are the same shade of dull green to bluish on both sides, lance-shaped to curved, long and wide, tapering to a petiole long. The flower buds are arranged on a thin, branched peduncle in groups of seven, the peduncle long, the individual buds on

pedicels In botany, a pedicel is a stem that attaches a single flower to the inflorescence. Such inflorescences are described as ''pedicellate''. Description Pedicel refers to a structure connecting a single flower to its inflorescence. In the absenc ...

long. Mature buds are pear-shaped to oval or spherical, long and wide with a rounded operculum with a point in the centre. Flowering occurs between September and January and the flowers are white. The fruit is a woody, shortened spherical or conical capsule long and wide with the valves near rim level.

Taxonomy and naming

''Eucalyptus microtheca'' was first formally described in 1859 by

Ferdinand von Mueller Baron Sir Ferdinand Jacob Heinrich von Mueller, (german: Müller; 30 June 1825 – 10 October 1896) was a German-Australian physician, geographer, and most notably, a botanist. He was appointed government botanist for the then colony of Vict ...

in the '' Journal of the Proceedings of the Linnean Society, Botany'', from samples he had collected in 1855 along the Victoria River in the Northern Territory. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

(''microtheca'') is from the Greek ''micro-'' meaning "small" and ''thece'' meaning "a box" referring to the small fruit. ''Eucalyptus microtheca'' is most closely related to the widespread '' E. coolabah'' which is found in similar but drier habitats to the south and south-east. It is also closely related to '' E. victrix'' which is found in even drier habitats from central Australia west to the

Pilbara The Pilbara () is a large, dry, thinly populated region in the north of Western Australia. It is known for its Aboriginal peoples; its ancient landscapes; the red earth; and its vast mineral deposits, in particular iron ore. It is also a glo ...

region of Western Australia.

Distribution and habitat

The tree is distributed widely across northern Australia and mostly found along river banks and in the heavy soils of flood plains. It is the second most widely distributed species in Australia after '' Eucalyptus camaldulensis''. The species is found waterlogged flats, along the margins of swamps in the Kimberley region of

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

. Populations of the tree are scattered through several IBRA regions including Dampierland,

Northern Kimberley The Northern Kimberley, an interim Australian bioregion, is located in the northern Kimberley region of Western Australia,Central Kimberley The Central Kimberley, an interim Australian bioregion, is located in the central Kimberley region of Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area ...

Ord Victoria plain The Ord Victoria Plain, an interim Australian bioregion, is located in the Northern Territory and Western Australia, comprising .

and

Victoria Bonaparte The Victoria Bonaparte, an interim Australian bioregion, is located in the Northern Territory and Western Australia,

. It is also distributed throughout the

top end The Top End of Australia's Northern Territory is a geographical region encompassing the northernmost section of the Northern Territory, which aside from the Cape York Peninsula is the northernmost part of the Australian continent. It covers a ra ...

of the

Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an states and territories of Australia, Australian territory in the central and central northern regions of Australia. The Northern Territory ...

east from the Western Australian border as far north as about

Newcastle Waters Newcastle Waters is a town and locality off the Stuart Highway in the Northern Territory. The nearest petrol station and accommodation is found south at Elliott. The Newcastle Waters School draws most of its few students from the Marlinja hom ...

and through the Barkly Tableland east through the catchment areas of the Roper and

McArthur River The McArthur River is a river in the Northern Territory of Australia which flows into the Gulf of Carpentaria at Port McArthur, opposite the Sir Edward Pellew Group of Islands. The river was named by Ludwig Leichhardt while he explored the are ...

s and into the Gulf Country of

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

. In Queensland the range of the plant extends from the Gulf Country to western Cape York and south to about

Mount Isa Mount Isa ( ) is a city in the Gulf Country region of Queensland, Australia. It came into existence because of the vast mineral deposits found in the area. Mount Isa Mines (MIM) is one of the most productive single mines in world history, bas ...

Uses

Indigenous Australian Indigenous Australians or Australian First Nations are people with familial heritage from, and membership in, the ethnic groups that lived in Australia before British colonisation. They consist of two distinct groups: the Aboriginal peoples ...

s harvested seeds from ''E. microtheca'' as a source of food. The wood produced by the tree is extremely hard and difficult to work with but is excellent for firewood and makes long-lasting fence posts that resist weathering and insects. The trees have a dense, rounded shape making them wind resistant and useful as

windbreak A windbreak (shelterbelt) is a planting usually made up of one or more rows of trees or shrubs planted in such a manner as to provide shelter from the wind and to protect soil from erosion. They are commonly planted in hedgerows around the edges ...

s and to control

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

. They are one of the more commonly planted eucalyptus species in the southwestern United States since they are fast and easy to grow. Able to tolerate full sun, withstand temperatures below freezing and grow in soils with poor fertility makes them easy to grow. Oils extracted from the leaves and blossom of the plant contain 101 compounds including

α-pinene α-Pinene is an organic compound of the terpene class, one of two isomers of pinene. It is an alkene and it contains a reactive four-membered ring. It is found in the oils of many species of many coniferous trees, notably the pine. It is also ...

, O-cymen, β-pinene, aromadendrene, α-phellandrene and globulol. Some of the chemicals isolated are utilised in medicinal and food products and others are alternatives to insecticide agents.

References

{{Taxonbar, from=Q928175 microtheca Drought-tolerant trees Myrtales of Australia Plants described in 1859 Taxa named by Ferdinand von Mueller