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Acacia aphylla

Leafless Rock Wattle

Family: Fabaceae subfamily Mimosoideae

Acacia aphylla is a wiry, narrow spiky shrub, to 3 m high.

It is endemic to Western Australia and it listed as threatened with extinction. It is found in two general areas about 60 km apart, east of Perth, one in the Hidden Valley area on the Helena River and the other south of Northam in Clackline Nature Reserve.

It is found on sandy, gravelly and clay soils, growing in eucalypt woodlands.

Australian Wattles at least, can be broadly placed into 1 of 3 recognisable groups:

  • Group 1: Those that produce juvenile compound-bipinnate leaves and then change to producing adult-phyllodes which are modified-flattened petioles which form the foliage. This is combined with flowers produced in globular balls or heads (or ovoid heads). The heads can be singular in leaf/phyllode axils or arranged in groups.
  • Group 2: As for Group 1 but flowers are produced in longer rod-like spikes.
  • Group 3: Those that never produce phyllodes and retain the juvenile compound-bipinnate foliage into adulthood. These always produce flowers in globular balls (which are secondarily arranged into panicle or raceme-like groups in many cases).

This wattle aligns mainly with Group 1. However, this wattle does not have any leaves (phyllodes or bipinnate leaves). Rather, the shrub consists of contorted, curvy rigid branchlets which are terete (tubular) and ribbed. The end of the branchlets are sharp / pointed.

Flowers are produced in globular heads, to about 8 mm in diameter, with up to 30 very small staminate flowers per head. The heads are produced singularly along the branchlets. The flowers are bright yellow, very showy and produced in late winter to spring.

Seed pods straight, to 9 cm long and to 0.4 cm wide.

In the garden

This species has a history of being cultivated and it is grown by some Sutherland members at least. It is a unique wattle to grow, in terms of its leafless foliage and twisted wiry branchlets. It has a very attractive complex structure. It is reported to be a quick growing plant and will last for several years at least. Plant in full sun or part sun, in a very well-drained sandy soil. It will be intolerant of damp areas and may not thrive in humid areas.

Acacias can suffer from a number of pests, including borers, scale, galls and leaf miners. Growing plants suitable to your local environment minimises these occurring.

Propagation

Propagation is easy from scarified seed by covering with boiling water for 24 hours and discarding any seeds still floating on the surface.

Other information

Most wattles will regenerate from seed after fire with some species exhibiting suckering from the base.

Acacia is a highly diverse genus, with over 1500 recognised species (placing it in the top-10 most-diverse plant genera) occurring in most continents except for Europe. Australia has about 970 spp., most of which are endemic. There are also about 10 exotic species. NSW has about 235 recognised species. Some species have become weeds in other states outside of their natural range (eg: wattles from Western Australia into NSW and vice versa).

Acacia – from Greek Akakia – which refers to an Ancient Greek preparation made from one of the many species; the name of which derives from akis, meaning “thorn” – referring to the thorns of species in Africa.

aphylla – Latin a– “without”) –phylla (leaves), referring to the species being leafless.

This species is listed as threatened under both Western Australian and Commonwealth legislation.

Western Australian Herbarium – Florabase – Western Australian Flora – Acacia aphylla profile page https://florabase.dpaw.wa.gov.au/browse/profile/3220

Gardening with Angus – Acacia aphylla profile page                https://www.gardeningwithangus.com.au/acacia-aphylla-leafless-rock-wattle/

Wikipedia – Acacia aphylla profile page                                        https://en.wikipedia.org/wiki/Acacia_aphylla

By Dan Clarke