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Acacias are a spectacular component of the flora of Australia, providing a flush of yellow to the landscape, often with a delightful scent as well. They have enormous variety from large forest trees to small shrubs suitable for a rockery and are very popular for growing in gardens.
Acacias are a major feature of the Australian flora, but they are not restricted to Australia. There are over 1500 species in the genus Acacia, world-wide, of which about 950 are Australian, over 130 in Africa, 100 in Madagascar, 270 in the Americas and 55 in the Asia/Pacific region.1
The Acacias have such an important placein the Australian flora that one species, the Golden Wattle - Acacia pycnantha (pictured on the right) was chosen as the floral emblem of Australia and has featured on some Australian stamps.
Acacias are mostly spectacular in flower and are often covered with flowers providing dense patches of some shade of yellow to cream, with a few exceptions. Flowers can be so dense as to almost conceal the foliage as in this Silver Wattle - Acacia dealbata in my garden.
Acacias are legumes, closely related to the many pea flowers and shrubs and also to the cassias. The flowers of the Acacias and its closest allies are very different from peas and cassias, in that the petals are greatly reduced and the flower is dominated by the conspicuous stamens. The flowers are compacted into usually dense heads (often globular) and the petals are almost completely concealed except in the bud stage. This close-up of the flowers of the Black Wattle – Acacia mearnsii show both buds and flowers. Black Wattle flower heads contain 20 to 40 flowers per dense flower-head, so that the short stem in the picture will contain nearly 200 flowers.
But although the individual flowers are tiny, the seed pods are quite large, up to 15 cm long for the Black Wattle and a tree can be weighed down by the weight of the pods, even if only 1 flower in each head is fertilised. Here is a picture of seed pods on a Silver Wattle. Each pod may hold up to about 12 seeds and the seeds have a hard dark coating. This coating prevents the seed from drying out and it is so effective that seeds can
lie in the soil for 50 years without germinating. A bush fire however may crack the outer coating and the next rainfall results in the seed germinating. There have been cases where a fire has crossed an area where Silver Wattle has not been seen for 50 years and suddenly a whole forest of Silver Wattle sprouts from the ground!
I have seen this longevity of the seeds for myself. Recently we wanted to grow some Blackwood – Acacia melanoxylon for a revegetation project and it had been a very poor year for Blackwood seed. A local farmer produced a packet of Blackwood seed that he had collected in the 1950’s. We treated some with boiling water as usual and most of the 50 year old seeds germinated.
You may have noticed that several of the Acacias referred to are called Wattles. In Australia, all Acacias are collectively known as wattles. This comes from the practice of early settlers in Australia of building houses using the ‘wattle and daub’ technique. The word 'wattle' is of Anglo-Saxon origin and refers to flexible lengths of branches woven between stakes for t
Female Ganggang Cockatoo
he construction of fences or walls, with an additional layer of mud or clay to weatherproof the house walls, hence the name ‘wattle and daub’.
Apparently the branches of Acacias were found the most suitable for this construction and the name wattle has been used for the Acacias ever since.
Despite the hard outer coating, there are still birds in Australia that feed on Acacia seeds.
The Gang-Gang Cockatoo visits our garden each year to feed on the Cootamundra Wattle – Acacia baileyana seeds and they also feed frequently on the seeds of the Black Wattle as seen here. But despite their powerful beak, they seem to choose to feed on the seed before they are fully ripe and before the hard outer casing has formed.
Common Bronzewing
The Common Bronzewing Pigeon also feeds on Black Wattle seeds, but it feeds on the ground, so the seed it finds are all ripe hard seed shed by the trees.
wattle trees have seeds edible to humans and many species were eaten by the indigenous people. The seeds were mostly thrown in a fire to crack the outer shell, then the kernels were ground and made into a paste to be baked into cakes. A ‘Bush Tucker’ industry has started up recently in Australia, and Wattle seeds are readily available. The species most often used is the Gundabluey or Bramble Wattle - Acacia victoriae (despite its wicked thorns).
Many species were important plants for the aboriginal people of Australia:
Acacia dealbataAcacia mearnsii Silver Wattle, MART Black Wattle, KORONG = gum Silver Wattle is common in mountain forests. Black wattle is widespread at low elevations. Both species were used in the same ways. The seeds were either ground to make flour for damper or steamed and eaten whole. The seedpod was split with a stone knife, the seeds beaten out, winnowed on bark and ground with grinding stones. Gum was eaten, sometimes mixed with mannas, or made into a sweet drink and left to ferment. The bark was used as a medicine, by making a decoction, used to slow major bodily processes and used as a remedy and treatment for diarrhoea, haemorrhage, heavy menstrual flow, as well as many other uses. The wood was used to make handles for implements and the inner bark was made into string.2
Blackwood was a favourite timber for the Ganai for boomerangs, shields and coolamons. The roots and bent branches were favoured for boomerangs. Bark was used to make fishing lines and for making a decoction for treating rheumatism. Bark and twigs were used as a poison for fish.2
The timber of Blackwood has become an important timber in modern Australia as it is very decorative and is often used in making quality furniture. The background of this marquetry document box, which I made, is an example of the use of Blackwood timber.
References:
1. Flora of Australia Volume 11A, Mimosaceae, Acacia part 1, Melbourne: ABRS/CSIRO Publishing (2001).
2. De Souza-Daw, R., Harris, K. and Paton, D. Plants of Significance to the Ganai Community. Woollum Bellum KODE School (2000)
About Kennedy Harris
I garden in Australia. I have a great love for all of nature, and have been photographing plants and animals for many years
Posted by FloridaCracker (from Cassadaga, FL) on March 11, 2008 at 1:13 PM:
Texas has a wild Acacia with a wonderfull, delicate perfume when in bloom in the spring and the seeds are loved by the wild turkeys. It grows in thickets and is covered with the yellow flowers. The honey bees flock to drink the nectar. It is very endangered by development which includes the making of pastures where it is bull-dozed by the acre. FloridaCracker (I love Texas, lived there over twentyfive years.)
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Subject: Thank you.
Posted by Lily_love (from Central, AL) on March 6, 2008 at 10:01 AM:
Thanks for such informative article. I'd definately save/tag such valuable information provided.
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Posted by rebeccanne (from Gold Beach, OR) on March 7, 2008 at 2:18 AM:
I very much enjoyed your article. I am hoping you will be inspired to write more on the flora of australia. I love your native plants and grow many in my garden, but need many, many more.
Thanks for writing this, I am going to need a wattle.
Rebecca
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Posted by kennedyh (from Churchill, Victoria
(Australia)) on March 7, 2008 at 4:10 AM:
Rebecca,
I have seed of a number of wattle species if you are interested,
Kennedy
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Posted by rebeccanne (from Gold Beach, OR) on March 7, 2008 at 3:40 PM:
Oh if I could get some seed from Australia it would be the grevellea, backea, leptospermum, etc. I just got a book of shrubs and trees of Australia and am afraid to look at it for all the things I will want. I love the plants from Australia and Chile. My uncle has quite a few wattle and I will go and see which ones he has, now that I know what to look for. Most of his reseed too well, so I will yank a few....thats easy.
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Posted by Fitsy (from Hayesville, NC) on March 11, 2008 at 11:44 AM:
Blackwood was a favourite timber for the Ganai for boomerangs, shields and coolamons. The roots and bent branches were favoured for boomerangs. Bark was used to make fishing lines and for making a decoction for treating rheumatism. Bark and twigs were used as a poison for fish.2
Acacias are a major feature of the Australian flora, but they are not restricted to Australia. There are over 1500 species in the genus Acacia, world-wide, of which about 950 are Australian, over 130 in Africa, 100 in Madagascar, 270 in the Americas and 55 in the Asia/Pacific region.1
