Acacia denticulosa

Sandpaper Wattle

Family: Fabaceae subfamily Mimosoideae

An open, somewhat sparse shrub to 4 metres high.

It is endemic to Western Australia and it listed as threatened with extinction. It is found in an area east of Mt Churchman, south to Nugarin and west to Wongan Hills in Western Australia, an area generally confined between Perth, Geraldton and Kalgoorlie. Here, it is found on sandy soils and granite outcrops, growing in semi-arid shrublands.

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 belongs to Group 2.

Phyllodes (modified leaves) are very atypical for a wattle, being large, crinkled and somewhat undulating, generally ovate in shape, to about 10 cm long and 8 cm wide. They are thick and scabrous / rough with a sandpaper and leathery texture. They also have toothed margins and are dark green.

Very small staminate flowers are produced in spikes (cylindrical heads), to 8 cm long, in leaf axils, consisting very small staminate flowers. The flowers are bright yellow, very showy and produced in spring.

Seed pods straight to slightly curved, to 8 cm long and less than 1 cm wide.

In the garden

This species has a history of being cultivated and it is grown by some APS-Sutherland members at least. It is a unique wattle to grow, in terms of its atypical foliage. It is reported to be a quick growing plant and will last for several years at least. Plant in full sun, in a 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.

denticulosa – Latin referring to toothed (roots of denticulate/dentistry) referring to the toothed margins (edges) of the phyllodes.

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

Australian National Herbarium – Acacia denticulosa profile page
https://www.anbg.gov.au/gnp/interns-2012/acacia-denticulosa.html

Gardening with Angus – Acacia denticulosa profile page https://www.gardeningwithangus.com.au/acacia-denticulosa-sandpaper-wattle/

Western Australian Herbarium – Florabase – The Western Australian Flora Acacia denticulosa profile page https://florabase.dpaw.wa.gov.au/browse/profile/3293

January 31, 2021