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Christmas Bells - Blandfordia nobilis

Monday, September 01, 2008

Happy Wattle Day

Today, 1 September, is Wattle Day in Australia.

I know Queenslanders and ex-Queenslanders will scream - "It should be 1 August". This issue came up at the Robertson Garden Club today, and so I decided to check it out. According to the Wattle Day Association, this issue was formally decided on an Australia-wide basis in 1992.
Here in the colder parts of NSW, many Wattles are flowering now. In fact, on my trip to Queensland last week, there were many Wattles in flower beside the roads. So the date seems appropriate.
Of course, as a former guide at the Australian National Botanic Gardens in Canberra I know that there are different species of Wattles (Acacias) which flower in each month of the year. But the reality is that the preponderance of the Wattles do flower in Spring.

Studies of buds of the Blackwood Wattle, (Acacia melanoxylon). The wattle blossom is clearly seen to be a composite flower, made up by many different flowers grouped into a rounded "head", dominated by a spray of anthers, each covered with pollen grains.
What one does not normally notice is the petals which rupture as the anthers mature, and push out to open. The botanists describe Wattle flowers and leaves in the following terms:
  • Flowers actinomorphic; petals valvate, equal; stamens usually numerous, forming the conspicuous part of the inflorescence; leaves often bipinnately compound or reduced to phyllodes.
As for their actual flowering times, I have published photos of Wattles in flower in my yard, over the last month, and some others in the bush, near the Boxvale Track, on 12 July.

Here are several Wattle trees in full flower, visible from several hundred metres away. These are probably A. decurrens (amended from A mearnsii - 24.7.09 - DJW), the same ones as I have growing in my backyard. The flowering season, and brilliant golden colour is distinctive from other popular fern-leaved Wattles which grow in this district (as planted, non-endemic).For those interested in researching the world-wide distribution of "Wattles" or "Acacia" species - (the generic name "Acacia" has been subjected to review by taxonomists), Australia has some 993 formally defined species of 1381 species world wide number of species. That is 72 percent of all known species are found in Australia. More significantly we have 975 species (out of 987 species worldwide) in the sub-genus "Phyllodineae" the group of wattles which have flat "false leaves" or "Phyllodes", as distinct from the "true leaved" species - the so-called "fern-leaved wattles". Here is the leaf of one of the so-called fern-leafed Wattles, Acacia decurrens.
Below is a close-up of a Wattle phyllode - it is a flattened stem.
The lower image shows the "gland",
the shape and location of which is distinctive of each different species.

6 comments:

mick said...

Great photos - especially the close-ups. I love the wattles - especially the perfume which seems to waft on the breeze from a fair distance away.

Gouldiae said...

G'day Denis,
Another great post in your thorough and informative manner - keep 'em coming.
The wattles are just wonderful harbingers of spring.
Gouldiae

Denis Wilson said...

Thanks Mick and Gouldiae.
It is the scent which most strongly influences me. I love the waft of Wattle perfume on the breeze. The European parfumiers use "mimosa" in some of their perfumes - from one of the prickly wattles which grows on the Arabian peninsula.
Of course, that just points to the Gondwanan origins of our Wattles. They started in Africa as ferny-leaved, often spiny plants. And when they arrived in Australia the climate changed, and (after the split from Gondwana) rapid adaptation produced great speciation, which is why we have so many of the Phyllode species. They are, arguably, our most highly adapted Australian plants - flat stems reduce transpiration; seeds survive fire and indeed need fire to trigger germination. Grey colouring on many species is as a result of a natural sun-screen. As I say, highly adapted to our dry continent.
Denis

Beth said...

I was starting to worry about you when you wheren't blogging. So it's great to have you back. Have you seen the Book "Orchids of Australia" by Banks and Briggs??? I saw it when I was visiting my sister on the weekend and the orchid illustrations are awesome!! I'm going to get the book in at the FFVC. Great photo's of the wattles I am so glad that you bought Dave's camera so that we can enjoy the wonderful photo's that you take

Denis Wilson said...

Hi Beth
Thanks. I was a way, then got back into blogging slowly. Glad you like the close-ups. It really is a whole other way of "seeing" things, such as buds, insects, and tiny flowers.
Cheers
Denis

Denis Wilson said...

Re the new Orchids book, no, I have not seen it. Sounds interesting.
Thanks for telling me about it.
Denis