Acacia hamiltoniana

Hamilton's Wattle

Family: Fabaceae subfamily Mimosoideae

Acacia hamiltoniana is a large shrub to 3 m high.

Its natural distribution is solely in NSW, in the Great Dividing Range and the associated foothills in western New South Wales, from around Rylstone in the north, down to around the Clyde River (between Braidwood and Batemans Bay) to the south.

It grows in sandy or loamy soils as well as sandstone outcrops, in dry sclerophyll woodland and forests.

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 1.

It has smooth, green variable phyllodes that have a linear to linear-oblanceolate or narrowly elliptic shape with a length to 8 cm and a width to 0.5 cm

Flowers are produced in globular heads, about 5 mm in diameter, with up to 15 very small, staminate flowers per head. Up to 11 heads are produced per raceme, emerging from leaf axils, between August and September.

Seed pods are black with a length of about 6 cm and a width of 1 cm.

In the garden

No details currently available for cultivation. It may be a species waiting to be cultivated or may have low potential. It would be an attractive plants in any home garden, in the right spot.

It likely needs a free-draining soil to thrive.

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

Many wattles regenerate from seed after fire and some exhibit suckering from roots and basal areas.

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.

hamiltoniana – named after Arthur Andrew Hamilton, (1855-1929) who was an Australian botanist. Hamilton collected the type specimen from around Leura in 1907.

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

NSW Flora Online (PlantNET) – Acacia hamiltoniana profile page http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Acacia%7Ehamiltoniana

Wikipedia – Acacia hamiltoniana profile page https://en.wikipedia.org/wiki/Acacia_hamiltoniana

Wattle – Acacias of Australia – Acacia hamiltoniana profile page https://apps.lucidcentral.org/wattle/text/entities/acacia_hamiltoniana.htm

January 2, 2021