Acacias

Course CodeVHT114
Fee CodeS2
Duration (approx)100 hours
QualificationStatement of Attainment

Learn to Identify, Grow and Use Acacias

Wattles can be grown for a range or amenity purposes (eg. land rehabilitation, decorative garden plants, windbreaks etc), timber production, a cut flower, for tanning, as a food (bush tucker plant), etc.

Their flowers are small, grouped in large numbers to create round balls or cylindrical spikes. These balls or spikes normally occur on peduncles (ie: a ball or a cylinder on the end of a stalk). They occur either singly, in pairs or racemes emerging from the axils of the leaves or phyllodes. The tiny flowers each have 4 to 5 sepals, 4 to 5 petals and numerous staemens. The fruit is a leguminous pod, often long. When mature, the pod will open releasing large hard coated seeds from inside.
In most species, there are no leaves. Instead, the plant has leaf like structures (considered to be modified petioles or leaf stalks), called "phyllodes".

Lesson Structure

There are 7 lessons in this course:

  1. Introduction
    • Review of the system of plant identification, information sources, etc.
    • Plant reviews
  2. Physiology of Acacias
    • Flower structure
    • Foliage types within the genus
    • Flower types within the genus
    • Acacia fruits
    • Plant reviews
  3. Culture
    • Planting, staking, mulching, watering, feeding, pruning, etc
    • Plant reviews
  4. Propagation
    • Methods of propagating Acacias.
    • Propagation of selected varieties.
    • Plant reviews
  5. Acacias in the Garden
    • Landscape uses
    • Plant selection
    • Acacias for different situations (Cold hardy, drought hardy, humid climates, summer flowering, autumn flowering, etc)
    • The Design Process
    • Plant reviews
  6. Other Uses for Acacias
    • Timber uses
    • Tanning
    • Cut Flowers
    • Food Source
    • Gum Arabic
    • Plant reviews
    • Pest & Diseases
    • Galls, Beetles, Weevils, etc
    • Environmental problems: Frost, Shade, Temperature, Wind
  7. Special Project
    • PBL project where you plan the establishment of a collection of different cultivars of Acacias suited to growing in a specified locality.

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.

Aims

  • Describe the way in which Acacias are classified.
  • Determine how to find reliable resource information that relates to Acacias
  • Describe the physiology of Acacias
  • Determine cultural requirements that are common to Acacias
  • Determine propagation methods that are commonly applicable to Acacias.
  • Describe a variety of commercial uses for Acacias.
  • Describe a range of other practical uses for Acacias.
  • Identify and recommend treatment for a variety of health problems occurring with Acacias.
  • Develop an in depth understanding of one aspect of Acacia Growing.

Acacias as Landscape Plants

A large range of Acacia species are widely used as landscape plants across the world. There are species suited to ally types of climates, from alpine to seaside; and snow prone places to topical climates. Here are just a few: 
 

Acacia baileyana (Cootamundra Wattle)

A small 5m tree, with dense grey foliage and showers of golden flowers at the end of winter. Forms with purple-tinted foliage are grown and are very decorative. One of the most popular wattles in most parts of the country, withstanding both drought and cold. It is not long-lived.

Acacia elata (Cedar Wattle)

A medium sized (10 10m tall and wide) tree with handsome green, ferny foliage and sprays of creamy flowers in summer. It is longer-lived than most acacias and makes a good shade tree. Fertile soils and mild climates suit it best.

Acacia longifolia

Small tree or large bush 4-10m tall, up to 7m spread with yellow tubular flowers from mid-winter to early spring. This wattle is fast growing and adapts to a wide range of sites from coastal to dry inland areas. Once established it will withstand periods of dryness.

Acacia pendula

A particularly attractive wattle with long weeping branches. 8-10m tall, tolerates both periods of dryness or wet, does best in full sun as a small to medium shade tree.

Acacia podalyriifolia (Queensland Wattle)

A small, rather slender tree to 4m, with silvery leaves and scented yellow blossoms in early spring. It prefers a warm climate, not being able to take much frost.

Acacia pycnantha (Golden Wattle)

A small (5m or so) graceful tree with long leaves and myriads of golden flowers in spring. Short-lived, it does well in most parts of Australia and is our national flower.

 

Edible Acacias
 
Wattle seeds have been harvested and eaten by aboriginal people for centuries in Australia. And used as fodder, famine and food crops in other countries particularly Africa. 
Around 10% of Acacias (i.e. approximately 50 species) are known to produce edible seeds. Of these, three have been more widely eaten than others. Some species are known to be toxic and many are simply not palatable. 
 
 
Acacia albida (Apple Ring Acacia)
A thorny tree to 25m (sometimes shrub-like); it is widespread throughout tropical and southern Africa and also Cyprus, Israel and Lebanon.
This is a much used tree in Africa and also used as a food crop by people in Rhodesia during times of famine. The seeds have approx. 27% protein and do not deteriorate nutritionally upon drying. The seeds are boiled twice firstly to more easily remove the skins and then again to remove the kernels. The seeds are ground as a flour and also used as a fodder crop for farm animals.
 
 
Acacia aneura (Mulga Wattle)  
Native to the arid outback areas of Australia a shrub like small tree to 15m was an important food source for indigenous people. 
Seeds can be ground to edible paste after first separating the seeds from the pods; seeds are roasted in hot ashes then ground into a paste whilst moistened with water. 
 
 
Acacia kempeana (Witchetty Bush)
The seed of this plant was an important food source for indigenous people (Australia). This is also known as the witchetty bush (the species hosts the grub which was also a food source).
This is a shrub that is rarely over 1.5 metres tall, but occasionally to 3 metres.
Flowers are cylindrical, yellow and to 6 cm long.
Frost tolerant and very hardy requiring little care once established.
Good dry inland semi-arid to arid temperate areas.
 
 
Acacia ligulata (Small Cooba, Sandhill Wattle, Dune Wattle)
A widely spread shrub native to Australia, but occurs mostly on sand hills across most of inland Australia (not the far north), it grows to between 1 and 4 metres high with orange or yellowish ball flowers. Seeds can be ground into edible paste.
 
 
Acacia longifolia (Sydney Golden Wattle)
A large shrub or small tree (6-8m tall) native to south eastern Australia and extending from the far South East of Qld. down to Victoria and in the South East of South Australia; it has long narrow phyllodes and narrow drooping seed pods.  It produces large, protein rich seeds - these seeds are bitter and can have a “sulphur” taste if eaten raw. Roasting or steaming the seeds makes them more palatable and gives them a nut like flavour. Roasted seeds can be used as a coffee like beverage 
 
 
Acacia murrayana (Murray’s Wattle, Colony Wattle)
From arid inland, central Australia; shrub of 2metres tall, or tree up to 7 metres with a 5 metre spread with glaucous, greyish foliage.
Seeds are ground to edible paste by Aborigines.  Grubs often attack in roots. This species is frost hardy but short lived.
 
 
Acacia victoriae (Gundabluie, Bardi bush)
Wide spread shrub that grows 2 – 5m tall and native to Australia; it suits semi-arid to warm temperate climates e.g. arid areas in Western Australia, Northern Australia Victoria  and South Australia. It has been cultivated commercially in the Flinders Ranges (South Australia) to harvest seeds also grown in Pakistan, Israel and Iran.
 
 
 
 
Harvest and Processing Wattle Seeds
  • Pods need to first be picked, dried (usually in the sun), and have seeds extracted.
  • The seeds then need to be cleaned (you only want clean seed so remove any dirt, pods, twigs etc).
  • The clean seed then should be cooked (either steamed or roasted).
  • Cooked seed may be stored for a period and packets of roasted seeds may be found for sale commercially at times.
The cooked seeds are commonly ground into a paste adding a small quantity of water as it is being ground.  The paste can then be frozen for later use. The paste has traditionally been made into small cakes and baked. Seeds can also be boiled to extract the flavour and create an ‘essence’ that can then be used for flavouring foods (e.g. ice cream) or as a beverage (e.g. wattle seed coffee).
 
 
 

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