''Eucalyptus polybractea'', commonly known as the blue-leaved mallee or simply blue mallee, is a species of mallee 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 south-eastern Australia. It has rough, fibrous or flaky bark on the lower part of the trunk, smooth greyish or brownish bark above, lance-shaped adult leaves, flower buds in groups of between seven and eleven, white flowers and cup-shaped or barrel-shaped fruit.

Description

''Eucalyptus polybractea'' is 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 rough, fibrous or flaky, greyish to brownish bark on the lower part of the trunk, smooth greyish to brownish bark above that is shed in ribbons. 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 repeated ...

regrowth have bluish to

glaucous ''Glaucous'' (, ) is used to describe the pale grey or bluish-green appearance of the surfaces of some plants, as well as in the names of birds, such as the glaucous gull (''Larus hyperboreus''), glaucous-winged gull (''Larus glaucescens''), g ...

, linear to lance-shaped leaves that are long and wide. Adult leaves are the same shade of bluish green on both sides, lance-shaped, long and wide, tapering to a petiole long. The flower buds are arranged in leaf

axil A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ...

s in groups of seven, nine or eleven on an unbranched 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 ...

up to long. Mature buds are club-shaped to diamond-shaped, long and wide with a conical to rounded operculum. Flowering mainly occurs from March to August and the flowers are white. The fruit is a woody, cup-shaped or barrel-shaped capsule long and wide with the valves near rim level.

Taxonomy and naming

''Eucalyptus polybractea'' was first formally described in 1901 by

Richard Thomas Baker Richard Thomas Baker (1 December 1854 – 14 July 1941) was an Australian economic botanist, museum curator and educator. Early life Baker was born in Woolwich, England, son of Richard Thomas Baker, a blacksmith, and his wife Sarah, née Colkett. ...

in ''

Proceedings of the Linnean Society of New South Wales The Linnean Society of New South Wales promotes ''the Cultivation and Study of the Science of Natural History in all its Branches'' and was founded in Sydney, New South Wales ( Australia) in 1874 and incorporated in 1884. History The Society suc ...

'' from specimens collected near

West Wyalong West Wyalong is the main town of the Bland Shire in the Riverina region of New South Wales, Australia. Located west of Sydney and above sea level, it is situated on the crossroads of the Newell Highway between Melbourne and Brisbane, and the ...

Richard Hind Cambage Richard Hind Cambage (7 November 1859 – 28 November 1928) was an Australian surveyor and botanist who made important contributions to the description of the genera ''Acacia'' and ''Eucalyptus''. Early life Cambage, son of John Fisher Camba ...

. 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 ...

(''polybractea'') is from the

ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

''poly-'' and the Latin ''bractea'', referring to the many bracts of this species, although many eucalytps have "many bracts" at the base of immature flowers. In 2018,

Kevin James Rule Kevin James Rule was born at Daylesford, Victoria on 9 November 1941. He was a secondary school teacher and had a particular interest in the taxonomy of Australian eucalyptus. He discovered several new species in Victoria. He is an honorary asso ...

described two subspecies, ''polybractea'' and ''suberea'' but the names have not been accepted by the

Australian Plant Census The Australian Plant Census (APC) provides an online interface to currently accepted, published, scientific names of the vascular flora of Australia, as one of the output interfaces of the national government Integrated Biodiversity Information Syst ...

Distribution

Blue-leaved mallee has a wide, but sporadic distribution around West Wyalong in New South Wales and between Stawell and

Bendigo Bendigo ( ) is a city in Victoria, Australia, located in the Bendigo Valley near the geographical centre of the state and approximately north-west of Melbourne, the state capital. As of 2019, Bendigo had an urban population of 100,991, makin ...

in Victoria. In grows in mallee shrubland on loamy soils.

Uses

Essential oil

''Eucalyptus polybractea'' leaves are used to produce

eucalyptus oil Eucalyptus oil is the generic name for distilled oil from the leaf of ''Eucalyptus'', a genus of the plant family Myrtaceae native to Australia and cultivated worldwide. Eucalyptus oil has a history of wide application, as a pharmaceutical, ant ...

with very high levels of

cineole Eucalyptol is a monoterpenoid. A colorless liquid, it is a bicyclic ether. Eucalyptol has a fresh mint-like smell and a spicy, cooling taste. It is insoluble in water, but miscible with organic solvents. Eucalyptol makes up ~70% - 90% of eucal ...

(up to 91%), yielding 0.7-5% fresh weight overall. The oil is primarily used medicinally and for flavoring.

Carbon sequestration Carbon sequestration is the process of storing carbon in a carbon pool. Carbon dioxide () is naturally captured from the atmosphere through biological, chemical, and physical processes. These changes can be accelerated through changes in land ...

This eucalypt is the most commonly planted tree in Australia as part of

carbon offset A carbon offset is a reduction or removal of emissions of carbon dioxide or other greenhouse gases made in order to compensate for emissions made elsewhere. Offsets are measured in tonnes of carbon dioxide-equivalent (CO2e). One ton of carbon ...

programs. Primarily, this is because the blue-leaved mallee is native to Australia, can grow effectively in drought conditions and can store a great deal of carbon quickly.

References

* Harden, G.J., ''Flora of New South Wales, Volume 2'', . {{Authority control polybractea Flora of New South Wales Flora of Victoria (Australia) Trees of Australia Mallees (habit) Myrtales of Australia Trees of Mediterranean climate Bushfood Crops originating from Australia Plants described in 1901 Taxa named by Richard Thomas Baker