''Eucalyptus crucis'' 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 else ...

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 ...

. There are three subspecies, commonly known as silver mallee or Southern Cross mallee, (subspecies ''crucis''), narrow-leaved silver mallee, (subsp. ''lanceolata'') and Paynes Find mallee, (subsp. ''praecipua''). It has rough bark that is shed in curling flakes, more or less round, glaucous juvenile leaves, egg-shaped intermediate leaves and lance-shaped adult leaves. The type of bark and the proportion of juvenile, intermediate and adult leaves in the

crown A crown is a traditional form of head adornment, or hat, worn by monarchs as a symbol of their power and dignity. A crown is often, by extension, a symbol of the monarch's government or items endorsed by it. The word itself is used, partic ...

of mature plants varies with subspecies. The flower buds are arranged in groups of seven in leaf axils, the flowers are whitish to pale yellow and the fruit is a conical to hemispherical capsule. Eucalyptus crucis buds

Description

''Eucalyptus crucis'' 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 rich, reddish brown, fibrous bark that in several subspecies is shed in curling "

minni ritchi Minni ritchi bark on an acacia in the Pilbara region of Western Australia Minni ritchi bark of ''Eucalyptus crucis'' near Wongan Hills Minni ritchi is a type of reddish-brown bark that continuously peels in small curly flakes, leaving the tre ...

" patches about wide. Young plants,

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, and sometimes the crown of mature trees have

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

, usually glaucous, more or less round leaves arranged in opposite pairs, long and wide. Intermediate leaves are arranged more or less in opposite pairs or alternately, egg-shaped to lance-shaped, up to long and wide with a short petiole. Adult leaves are arranged alternately, lance-shaped, long and wide on a petiole long. The flower buds are arranged in leaf axils in groups of seven on an unbranched peduncle long, the individual buds on a

pedicel Pedicle or pedicel may refer to: Human anatomy *Pedicle of vertebral arch, the segment between the transverse process and the vertebral body, and is often used as a radiographic marker and entry point in vertebroplasty and kyphoplasty procedures ...

long. Mature buds are more or less oval, long and wide with a conical to rounded operculum long. Flowering occurs between September and March and the fruit is a woody cup-shaped to hemispherical capsule long and wide.

Taxonomy and naming

''Eucalyptus crucis'' was first formally described in 1923 by

Joseph Maiden Joseph Henry Maiden (25 April 1859 – 16 November 1925) was a botanist who made a major contribution to knowledge of the Australian flora, especially the genus ''Eucalyptus''. This botanist is denoted by the author abbreviation when citing ...

from a specimen collected near

Southern Cross Crux () is a constellation of the southern sky that is centred on four bright stars in a cross-shaped asterism commonly known as the Southern Cross. It lies on the southern end of the Milky Way's visible band. The name ''Crux'' is Latin for ...

by Henry Steedman in 1922. Maiden published the description in his book ''A Critical Revision of the Genus Eucalyptus''. The specific epithet (''crucis'') is a

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 ...

word meaning "cross", referring to the type location. In 1982,

Ian Brooker Murray Ian Hill Brooker AM (2 June 1934 – 25 June 2016), better known as Ian Brooker, was an Australian botanist. He was widely recognised as the leading authority on the genus ''Eucalyptus''. Ian Brooker was born in Adelaide, South Australi ...

and Stephen Hopper described two subspecies, ''crucis'' and ''lanceolata'', and in 1993 they described subspecies ''praecipua''. The three subspecies have 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 ...

. * ''Eucalyptus crucis'' subsp. ''crucis'' has a crown composed of glaucous juvenile leaves; * ''Eucalyptus crucis'' subsp. ''lanceolata'' has a crown of greyish green adult leaves; * ''Eucalyptus crucis'' subsp. ''praecipua'' has a crown of adult leaves but they are larger than in subspecies ''lanceolata'' and the bark is only the "minni ritchi" type on the thinner branches.

Distribution and habitat

Silver mallee is found in an area in the Goldfields-Esperance and Wheatbelt region of Western Australia where it grows in sandy, clay or loam soils amongst

granite Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies under ...

outcrops. It is associated with sheoak (''

Allocasuarina ''Allocasuarina'' is a genus of trees in the flowering plant family Casuarinaceae. They are endemic to Australia, occurring primarily in the south. Like the closely related genus '' Casuarina'', they are commonly called sheoaks or she-oaks. ...

'' species), wattle ('' Acacia'' species) and one-sided bottlebrush ('' Calothamnus'' species). Subspecies ''crucis'' is only found between Merredin, Southern Cross and Westonia, subspecies ''lanceolata'' between Corrigin, Mount Churchman and Chiddarcooping Rock. Subspecies ''praecipua'' is only known from near Paynes Find.

Conservation status

Subspecies ''lanceolata'' is classified as "not threatened" but subspecies ''crucis'' and ''praecipua'' are classified as " Threatened Flora (Declared Rare Flora — Extant)" by the

Department of Environment and Conservation (Western Australia) The Department of Environment and Conservation (DEC) was a department of the Government of Western Australia that was responsible for implementing the state's conservation and environment legislation and regulations. It was formed on 1 July 2006 ...

. Subspecies ''crucis'' (silver mallee) is also listed as "vulnerable" under the Australian Government

Environment Protection and Biodiversity Conservation Act 1999 The ''Environment Protection and Biodiversity Conservation Act 1999'' (Cth) is an Act of the Parliament of Australia that provides a framework for protection of the Australian environment, including its biodiversity and its natural and cult ...

. The main threats to this subspecies are recreational activities, pipeline maintenance, grazing and weed invasion.

Use in horticulture

This eucalypt is frost and

drought A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...

tolerant and is suitable for alkaline soils. It is commonly used as a windbreak, a street tree, for its decorative fruit, for erosion control, and as a honey producing or bird nesting plant.

References