Acacia longissima

Long-leaf wattle or Narrow-leaf wattle

Family: Fabaceae subfam. Mimosoideae

A tall shrub to tree, reaching 6 m tall, spreading to several metres wide.

In NSW, it grows near the coast and is found as far north as Nambour and Nerang in south-eastern Queensland, extending down the south coastal areas of New South Wales to around Batemans Bay.

It is often found to inhabit the borders of rainforests in wet or dry sclerophyll forest.

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 2.

The phyllodes (modified leaves) are thin and dark green and are usually straight with a length to 18 cm, and a width to 1 cm.

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 linear spikes consisting of many small staminate flowers. Spikes are produced singularly or in pairs, in the axils of phyllodes, to 5 cm long, pale yellow to white and occur between January and May.

Seed pods are straight or slightly curved and usually 14 cm long, to 0.4 cm wide.

In the garden

Attractive slender erect small tree suited to gardens in a full sun/shade position with some moisture and even waterlogged soils.

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 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 (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.

longissima – Latin for “longest” referring to the long narrow phyllodes of this particular species.

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

Wikipedia – Acacia longissima profile page https://en.wikipedia.org/wiki/Acacia_longissima

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

January 27, 2021