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Acacia pycnantha

Golden Wattle

Family: Fabaceae subfamily Mimosoideae

Acacia pycnantha is a variable shrub to tree, reaching a height of 8 metres with a wide spread. This particular species is the basis for Australia’s floral emblem.

In NSW, it is found primarily on the south-western slopes and southern tablelands of NSW. Occurrences on the central western slopes, central coast, as well as, north-far western plains, are thought to be introductions. Acacia pycnantha occurs naturally over much of Victoria and extends into South Australia, as far west as Streaky Bay. This species has naturalised outside its natural range. It is a weed in Western Australia and South Africa.

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).

Phyllodes and bipinnate leaves are always alternate to clustered, never opposite.

This wattle belongs to Group 1.

The phyllodes are up to 20 centimetres long, broadest in the middle and tapering at both ends. Each phyllode has a prominent gland near the base of the phyllode. They are visible on the two lower phyllodes in the photograph provided.

Acacia spp. produce small 5-merous flowers, with 5 very small petals partly-fused into a short tube which sits above a fused calyx. The stamens are the main feature which are produced in high numbers per flower (staminate flowers), surrounding a single style.  In this species, flowers are produced in globular heads, golden yellow, with up to 80 flowers per head with heads to 10 mm in diameter. Heads are clustered into axillary racemes and well as terminal racemes or panicles, of up to 25; flowering in spring.

Pods are long and narrow, to 15 cm long and only to 1 cm wide.

In the garden

Reportedly easy to grow. It grows fast on a range of soils, provided drainage is adequate. It may be short-lived.

It grows best in temperate areas as well a semi-arid areas.

Excellent for creating habitat for insects. It flowers spectacularly. Grow in full sun for best results.

After the flowers fade, they should be cut off to promote fresh growth and maximum flowering.

Propagation

Propagate from seed that should be soaked in boiling water before sowing.

Other information

The bark has been used for tanning leather and the foliage for dyeing. Early settlers used a bark extract to treat diarrhoea and dysentery.

The type was collected near Wedderburn, west of Bendigo, Victoria and named in 1842.

Most wattles will die in a fire and regenerate from seed. Some species exhibit suckering from basal parts and roots.

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 (e.g., 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.

pycnantha – from Greek pycnos (πυκνοϛ) – meaning “dense” and antha – Greek (via Latin) anthir (ανθήρ) meaning “anthers” (or “flowers”) – referring to the dense nature of the globular heads (up to 80 flowers per head!)

This species is not considered to be at risk of extinction in the wild.

NSW Flora Online (PlantNET) – Acacia pycnantha profile page            https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Acacia~pycnantha

Botanic Gardens of South Australia – Plant Selector – Acacia pycnantha profile page http://plantselector.botanicgardens.sa.gov.au/Plants/Details/2715

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

 

By Warren and Gloria Sheather. Editing and additional text by Dan Clarke.