''Eucalyptus crucis'' is a species of mallee that is endemic to Western Australia. 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 ''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 ...

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 of mature plants varies with subspecies. The flower buds are arranged in groups of seven 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, 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. It has rich, reddish brown, fibrous bark that in several subspecies is shed in curling " minni ritchi" patches about wide. Young plants, coppice regrowth, and sometimes the crown of mature trees have sessile, 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 Peduncle may refer to: *Peduncle (botany), a stalk supporting an inflorescence, which is the part of the shoot of seed plants where flowers are formed *Peduncle (anatomy), a stem, through which a mass of tissue is attached to a body **Peduncle (art ...

long, the individual buds on a pedicel 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 from a specimen collected near Southern Cross by

Henry Steedman Henry Steedman (1866–1953) was a Scottish-born Australian botanist. Born in Scotland in 1866, he emigrated to Western Australia at the age of 21. He was head gardener at the South Perth Zoological Gardens (now Perth Zoo) for many years, but w ...

in 1922. Maiden published the description in his book ''A Critical Revision of the Genus Eucalyptus''. 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 ...

(''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 ...

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

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 ''Acacia'', commonly known as the wattles or acacias, is a large genus of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa and Australasia. The genus n ...

'' species) and one-sided bottlebrush (''

Calothamnus ''Calothamnus'' is a genus of shrubs in the family Myrtaceae and is endemic to the south-west of Western Australia. The common names one-sided bottlebrush or claw flower are given to some species due to their having the flowers clustered o ...

'' 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