''Acacia aphylla'', commonly known as the leafless rock wattle, twisted desert wattle or live wire, is a species of '' Acacia'' which is endemic to an area around

Perth Perth is the capital and largest city of the Australian state of Western Australia. It is the fourth most populous city in Australia and Oceania, with a population of 2.1 million (80% of the state) living in Greater Perth in 2020. Perth i ...

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 ...

Description

''A. aphylla'' is spiny and

leaf 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, ste ...

less erect and widely branching shrub that grows to in height and with a width of approximately . The generally bright green branchlets are rigid,

terete Terete is a term in botany used to describe a cross section that is circular, or like a distorted circle, with a single surface wrapping around it.Lichen Vocabulary, Lichens of North America Information, Sylvia and Stephen Sharnoff/ref> This is u ...

and obscurely ribbed. They are smooth, glaucous,

glabrous Glabrousness (from the Latin '' glaber'' meaning "bald", "hairless", "shaved", "smooth") is the technical term for a lack of hair, down, setae, trichomes or other such covering. A glabrous surface may be a natural characteristic of all or part of ...

and coarsely pungent. Unlike most ''Acacia'' the phyllodes are absent for ''A. aphylla'. The thickened blue-green wiry stems have the ability to photosynthesize like leaves so giving the plant an evolutionary adaptation that greatly reduces the total surface area for water loss through transpiration. ''A. aphylla'' produces yellow spherical

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s between August and October (late winter to mid spring) in its native range. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...

s have a simple structure with one per axil. The peduncles are long and glabrous with globular heads. They hold 20–30 flowers that are a bright light golden colour. The flowers are 5- merous with free

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coine ...

s. Seed-pods form later that are linear, long and wide containing black seeds that are longitudinal and oblong and about long. Pods are mature from December to March. Plants are mostly killed by fire but populations will regenerate from the soil seedbank.

Range

The shrub has a restricted range and is only found in two areas in the

Darling Range The Darling Scarp, also referred to as the Darling Range or Darling Ranges, is a low escarpment running north–south to the east of the Swan Coastal Plain and Perth, Western Australia. The escarpment extends generally north of Bindoon, to t ...

about apart from each other. The areas are both to the east of

with one population being found in Hidden Valley area in the

Helena River The Helena River is a tributary of the Swan River in Western Australia. The river rises in country east of Mount Dale and flows north-west to Mundaring Weir, where it is dammed. It then flows west until it reaches the Darling Scarp. It passes ...

and the other south of Northam in the Clackline Nature Reserve. The exact placement of each population is being withheld by the state government for conservation reasons.

Ecology

''A. aphylla'' is commonly found in open forest communities that are dominated by ''

Eucalyptus marginata ''Eucalyptus marginata'', commonly known as jarrah, djarraly in Noongar language and historically as Swan River mahogany, is a plant in the myrtle family, Myrtaceae and is endemic to the south-west of Western Australia. It is a tree with rough ...

'' and '' Eucalyptus calophylla'', or in woodlands where ''

Eucalyptus loxophleba ''Eucalyptus loxophleba'', commonly known as York gum, daarwet, goatta, twotta or yandee, is a species of tree or mallee that is endemic to Western Australia. It has rough bark on the trunk, smooth olive to brownish bark above, lance-shaped adul ...

'' dominates. Species commonly found in the understorey include '' Grevillea endlicheriana'', '' Hakea petiolaris'', and ''

Xanthorrhoea preissii ''Xanthorrhoea preissii'', known as balga, is a widespread species of perennial monocot in Southwest Australia. Description The form of the plant resembles a tree, with very long and bunched, grass-like, leaves that emerge from a central bas ...

''. It is generally associated with areas of laterite and granite outcrops on hillsides, and will grow in rock crevices. It is mostly found to grow in soils that are sandy, loam, clay, or gravel and brown or yellow in colour.

Cultivation

''A. aphylla'' is cultivated as a foliage plant, although it is actually succulent and is adapted to harsh conditions. It grows fast, requires well-drained soils and will tolerate full sun. It can be pruned following flowering and pruning can be harsh, back to approximately from the ground. Regrowth will take place in the next couple of months. It is both

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 ...

and frost tolerant and can be grown from seed. It produces an abundance of seed during summer which stores well and remains viable for many years. It regenerates poorly in habitat and often there are few or no seedlings to be found. When cultivated, the hard black seeds need to be soaked for 24 hours, with initially boiled hot water, to soften the coating, which usually gives a consistent and early germination of seeds.

History

The species was first described the species in the journal ''Nuytsia'' by the botanist

Bruce Maslin Bruce Roger Maslin (born 3 May 1946) is an Australian botanist, known for his work on ''Acacia'' taxonomy. Born in Bridgetown, Western Australia, he obtained an honours degree in botany from the University of Western Australia in 1967, then to ...

in 1974. The name ‘aphylla’ in

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 ...

means without leaves, due to the absence of phyllodes. ''A. aphylla'' was recorded as rare in 1950 and after 1992 it was listed as vulnerable then became protected under the ''Endangered species Protection Act 1992''.

References