Being such a large group of plants, there are sure to be many uses made of wattles by humans. In fact the Australian Wattles in particular offer such great possibilities that they are grown in 70 countries around the world where they currently cover around 2 million hectares in plantations. These species represent a vast genetic resource that offers considerable environmental, ecomonic and social benefits for the world. What are they? Here are some examples.
Wattles are grown for their wood
There are large plantations of Acacia mangium (Mangium) in tropical Asian countries such as Indonesia and Malaysia while Acacia melanoxylon (Blackwood) is cultivated in temperate countries such as Brazil, Chile, South Africa, New Zealand and parts of Australia. These and other species are grown for their timber that can be used in house construction, furniture making, paper pulp, fibre board manufacture, cellulose for rayon, charcoal and firewood for village communities. Blackwood produces a high quality cabinet timber from which very beautiful furniture is made, especially in Tasmania!
Wattles are grown for their bark
Large plantations of Acacia mearnsii (Black Wattle) are grown in Brazil, China, Vietnam, South Africa, Kenya, and India for bark. The bark is usually harvested at 8-10 years by ripping from the tree in long strips. The trees are then clearfelled for the timber. Bark is cut into short strips and spread on racks to dry. The dry bark is then bundled and sent to tanneries to be chipped and bagged. Tannins are then extracted by steaming or adding boiling water to chips in large vats connected in a series. The resulting 'liquor' is passed progressively through several large containers and finally to storage where the bulk of the water is evaporated off. The extracted tannin is largely used for tanning leather, but can also be used in making adhesives, preserving ropes and nets, making dyestuffs, corrosion inhibitors and as pharmaceutical products.
In years gone by Australia had an extensive tannin industry based mainly on Black Wattle harvested from the wild. The left over bark from the tannin extracting process was called tanbark. This was often reused as a mulch or path covering. The Tan, the 4 km path around the Royal Botanic Gardens in Melbourne was once spread with tan bark.
Walking on wattle!
Wattles are grown for their foliage
Herbivorous animals like making a meal of wattles. Foliage and green pods are eaten by stock animals around the world. In Australia, Mulga (Acacia aneura) is popular and useful as a fodder plant, especially in drought years in the Arid Zone. There are many other fodder acacias in Australia.
Wattles are grown for their seeds
Acacia seeds have a high nutritional value, and are good sources of protein, fat and carbohydrate. Australian Aboriginal use of seeds of many Wattles and their knowledge has been widespread, even to sub-Saharan Africa, where species such as Acacia colei, Cole's Wattle, is showing promise as a new human food. The bushfood industry in Australia particularly likes Gundabluey Acacia victoriae where the ground and roasted seeds are used for flavouring sauces and ice cream, in breads, pasta and biscuits. Acacia seeds are good in diabetic diets. The occasional wattle, though, is poisonous such as Georgina Gidgee Acacia georginae. More research is needed!
Wattles are grown for their flowers
Florists love bright fragrant flowers in their shops. In southern Europe wattles are known as mimosa and are grown for the cut flower trade. The Australian Acacia baileyana (Cootamundra Wattle), Acacia dealbata (Silver Wattle), Acacia pycnantha (Golden Wattle) and Acacia retinodes (Wirilda Wattle) are common there. Unfortunately some of these species have become environmental weeds.
In southern France, Acacia dealbata and Acacia farnesiana are used in perfume and fragrant oil production.
Wattles are grown for their form and beauty
Because Wattles come in many shapes, sizes and colours they offer great scope for growing in home garden, parks, botanic gardens, along streets and road verges.
Many wattles are fast growing therefore you can have 'instant' cover, e.g. A. boormanii (Snowy River Wattle); problem here is that fast growing species. are often short-lived
- Some are very long-lived therefore good for amenity planting, e.g. A. coriacea (especially subsp. pendens with its beautiful weeping foliage)
- Some wattles have spectacular bark colours (e.g. Minni Ritchi, A. cyperophylla, or white, A. gardneri, Gardner's Wattle)
- Growth form varies amazingly from prostrate which are good for ground covers (e.g. A. pulviniformis) to tall trees; some have very dense crowns while on others such as the 'Ghost Wattles' you can scarcely see the crowns (e.g. A. sciophanes, A. phasmoides)
- Phyllode form varies amazingly, some looking like plunging dolphins (A. delphina, Dolphin Wattle) or elephant ears (A. dunnii, Dunn's Wattle or Elephant-ear Wattle)
- There is great beauty in the colour of the new growth: golden in A. citrinoviridis (River Jam), red in A. myrtifolia (Myrtle Wattle) for example; in pod form (masses of variation); similarly the colour of the mature foliage varies tremendously, ranging from blue (A. boormanii again) to bright green (A. decurrens, Black Wattle).
- Wattles can smell beautiful not just because of their flowers, e.g. vanilla scent of A. redolens or aromatic resinous smell of Acacia dictyophleba..
- There are so many wattles to choose from that you could plant your garden so that some are flowering at all times of the year.
Wattles are grown for their hardiness
Acacias can thrive under adverse soil conditions. Combine this with their rapid growth due to nitrogen fixing root nodules, wattles can grow where no tree has thrived before. Sand stabilisation, grass control, mine sites, and importantly dryland salinity control are uses humans ask of acacias. In Pakistan, the Australian Acacia stenophylla (River Cooba) grows very well in high saline soils.
Wattles are grown to improve the environment
Because many wattles are such good pioneer species (i.e. they make fast early growth in disturbed sites) they are good for use in regenerating areas (e.g. roadverges, minesites) to stabilize the soil, to provide shelter belts and visual screens, and to provide wildlife habitats. The southern Australian wattles were recently assessed for their potential as new woody for use in salinity control: mainly for growing in strategic parts of the landscape (recharge areas mainly) to prevent water from entering the ground water system - some of the most promising species were Acacia saligna (Coojong), A. leucoclada subsp. leucoclada (Northern Silver Wattle), A. linearifolia (Stringybark Wattle), Acacia retinodes (Wirilda) and Acacia salicina (Cooba). Increasing salinity is one of the most serious environmental issues facing Australia today and Wattles have a part to play in addressing this problem.
Wattles are grown for their gum
Gum is eaten by all traditional societies native to acacia areas, it is also used as a glue. In Africa, gum arabic is harvested by artificially wounding the Acacia trees, collecting the tears of gum and transporting them to centres where they are cleaned and processed. Gum arabic is is commonly used as a thickener and emulsifier in prepared food products, confectionary, soft drinks, ice cream, cosmetics, toothpaste, soap, adhesives (eg. postage stamps), paints, ammunition and explosives, polishes, medicinal products, and industrial printing. Acacia senegal from Africa is the world's major source of this very valuable gum arabic.
Wattle gum is a complex polysaccharide and its origin as an exudate is not clear. Many Wattles (e.g. A. microbotrya, Manna Wattle) are capable of producing plentiful quantities of gum. Yum by gum!
Wattles are grown for medicine
The tannin rich inner bark and gums of wattles have therapeutic effects, and this has been known to Indigenous peoples since time immemorial. Bark can alleviate diarrhoea, gums can soothe inflamed skin. The Zulu of Africa use Acacia caffra as an emetic, and give the leaves to their children for tummy troubles.
In more recent times, Gum Arabic has been used as a major component of artificial blood serum. Sap from the phyllodes of the Hawaiin Acacia koa can inhibit Golden Staphylococcus bacteria, and there are recent reports that Acacia victoria in Australia can produce chemicals called triterpenoid saponins that inhibit tumour growth. More bioprospecting needs to be done!
Wattle you know wattle you do?
- If you have ever licked a postage stamp, you have licked a wattle. How many ways do people use wattles? Draw up a table of uses of wattles.