Acacia cultriformis, the Knife-leaf Wattle, is a bushy, medium to tall shrub, to 4 metres tall by 4 metres wide.
Acacia cultriformis occurs mainly on the western slopes of NSW extending into the north western plains and southern tablelands, from location such as Albury through West Wyalong to Wee Waa. It extends into Queensland into southern Queensland but only as far as between Stanthorpe and Inglewood. It appears to have several growth habits. In the Warrumbungle National Park, central NSW, plants are tall, upright shrubs. Planted specimens, near Tamworth, also central NSW, are rounded shrubs reaching a height of two metres. It has naturalised outside of its natural range and is considered to have weedy potential.
It grows in dry sclerophylll woodland as well as mallee-shrublands and heathlands, often on rocky sites as well as sandy soils.
Australian Wattles at least, can be broadly placed into 1 of 3 recognisable groups:
This species belongs to Group 1.
The triangular-shaped phyllodes (hence the common name) are crowded along the branches. The size of the phyllode varies from 20 to 30 millimetres long by 6 to 14 millimetres wide and bluish green in colour. There is a prominent gland on the upper margin.
The inflorescences comprise up to 40 very small staminate flowers carried in the globular heads. The heads, on some plants, are almost oval in shape. The heads are in racemes of up to 25 in leaf axils; bright yellow and cover plants in mid spring.
The pods, that follow the flowers, are linear and up to 70 millimetres long (see thumbnail).
Author’s notes: The specimens, in our cold climate garden (near Armidale), are tall shrubs with slightly pendulous branches.
This species is a very showy plant to grow. Plants are very daxxling when in full bloom and the grey sharply-shaped foliage also creates interest. It is very hardy on a range of soils. Grow in an open area in full sun for best effect.
Just note – it can be a weed outside its natural range. Good garden practice can include cutting off seed-pods before they are mature.
Propagation is easy from scarified seed by covering with boiling water for 24 hours and discarding any seeds still floating on the surface.
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 (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.
cultriformis – Latin – cultri – meaning “knives” and –formis – “form” – referring to the knife-shaped phyllodes of this plant.
This species is not considered to be at risk of extinction in the wild.
NSW Flora Online (PlantNET) – Acacia cultriformis profile page https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Acacia~cultriformis
Wrigley, J.W. & Fagg, M.I. (2001). Australian Native Plants – Propagation, cultivation and use in landscaping. 4th edition. New Holland Publishers, Pty. Ltd. Australia.
Australian National Herbarium – Acacia cultriformis profile page https://www.anbg.gov.au/acacia/species/A-cultriformis.html