Acacia holosericea

soapbush wattle


Acacia holosericea

G.Don 1832

pronounced: uh-KAY-shuh hoh-low-ser-ee-KEE-uh

(Mimosaceae — the wattle family)

common names: soapbush wattle, strap wattle, candelabra wattle

native 4Acacia comes from the Greek ακις (akis), a thorn or spike; holosericea is from the Greek word 'ολος (holos), whole, complete, and the Latin word sericeus, silky.

This is a spreading shrub that reaches a height of about 3 m, and has a spread of about 4 m. It is very quick-growing, but fairly short-lived. The easiest ones to find on the island are on the end of the right-hand breakwater as one leaves the Nelly Bay harbour. It is native to Queensland, the Northern Territory, and the northern parts of Western Australia. This plant is one of those collected in 1770 by Banks and Solander during the voyage of the Endeavour. It was collected at the Endeavour River (Cooktown).

When the seedlings first emerge, the cotyledons are oblong, 4 - 5 mm by 2 - 3 mm in size, the apex acute, and the base sagittate or auriculate. The first leaf is pinnate, the second one bipinnate. By the sixth or seventh leaf stage, with the leaves still bipinnate, the petiole is broadly flattened, and by the tenth leaf stage the petioles are changing into phyllodes. These are grey-green in colour, ovate-lanceolate in shape, with 3 or 4 prominent veins, and can be quite long, 10 - 25 cm in length. All parts of the seedling are usually covered in silky white hairs, as are the mature phyllodes.

The flowers are rod-like and bright yellow, 3 – 6 cm long. They usually appear between May and July.

The seed-pods are 3 – 5 cm long, twisted, curled and sticky, and masses of these pods will remain on the plant even after the seed has fallen. Children in the Mount Isa area refer to the pods as ‘soap’ (hence the common name), as, when the pods are at the sticky stage, rubbing them between the hands helps to remove dirt. The name ‘candelabra wattle’ is used around Alice Springs. I suspect this is because of the appearance of the tree when in full flower, with all the inflorescences standing upright like candles. I have no idea where ‘strap wattle’ comes from.

In some areas this was a very important plant to the Aboriginal peoples. A concoction of leaves and pods was put into the water to kill small fish. The seeds are very nutritious, and can be roasted, boiled like lentils, or steamed with vegetables. The roasted seeds have a nutty flavour popular with children who have little access to sweets. The species has been introduced into parts of Africa by Australian aid agencies as a food-producing plant – the protein content is 17–25%. It is hoped to use the plant extensively there in revegetation schemes.

This is a very suitable shrub for largish gardens in tropical areas, with its quick growth, spectacular foliage and bright yellow blossom. It also has an attractive shape, which a little light judicious pruning would keep in order where necessary. Propagation is done from seed, but the seeds need to be soaked in boiling water to soften the hard seed coat.

This is a food tree for the larvae of Jalmenus eichhorni, the Northern Imperial Blue butterfly.


Photographs taken at Nelly Bay 2009-2013, Picnic Bay 2016
Page last updated 23rd September 2018