Our Bushland Diary


Saturday, May 2, 2009

The very variable Firewood Banksia

I adore banksias. One of my earliest memories is playing in a cool sandpit under a big banksia tree, listening to wattlebirds clucking away above me, and using the fallen cones as turrets for my sandcastle.

May Gibbs depicted banksias as evil characters in her childrens' books, but to me they've always been a reminder of ancient times in the rough leathery honey-scented wonderland that is the Australian bush. Fossil banksias in the WA Museum are eerily similar to the ones growing in our local bushland.

Banksias provide food (nectar, pollen, seeds, leaves) for a large variety of animals, including bees, butterflies, beetles, honeyeaters, parrots, cockatoos and possums. Interestingly, the suite of banksias found in Ellenbrook have overlapping flowering times; this ensures that
tiny Honey Possums and Brown Honeyeaters always have something to eat. Geckoes, small skinks, spiders and insectivorous birds, too, are attracted to banksias for the feast of insects.

You can find at least two banksias in flower in Ellenbrook at the moment (in May). Moulton Wetland is a good place to view the Swamp Banksia (Banksia littoralis) - dark yellow inflorescences (flowers), and the Firewood Banksia (B. menziesii) - (usually!) pink/orange inflorescences.

That's the Firewood Banksia (or Menzies' Banksia) to the left. Notice that the flowers open from the bottom and slowly work their way up to the top. Wouldn't it be interesting to do a time-lapse photo series and watch the flowers open?


Firewood Banksia flowers are variable in colour - some trees have very dark- or very light-coloured inflorescences. You might be lucky enough to find a Firewood Banksia with yellow flowers.

I always look for these when I'm out in the bush, but they are difficult to find as they aren't very common. There are only a few scattered in the nearby Bush Forever Sites.

There's one in Moulton Wetland.

There's another one in the bushland just north of Fewson Turn (Charlotte's Vineyard) which you can spot from the road if you have a sharp eye. Here's a photo of it (right).

Now, here's an even rarer prize. . . I would love to hear from you if you find one of these in your treks around Ellenbrook or neighbouring suburbs. (Add your comment at the end of this post.)

It's this - a "copper" (or "bronze") (left, and below right).









So far, I have seen only two trees, but unfortunately both are in bush remnants which are likely to be bulldozed in the next few years. I'm guessing there are others in Bush Forever Sites, fingers crossed.

I have heard that there is a fourth colour type, called "chocolate" (yummy!), and I can't wait to find that one!


But seriously, I wonder about the science behind these prehistoric trees. All the colours apparently breed true, that is, if you take seeds from a "yellow" tree, they will also be "yellow" trees. What would be the evolutionary advantage of having variable colours, if any? Do different colours attract different animals? Have the proportions of pink vs. yellow. vs. copper vs. chocolate changed over the centuries? (Imagine a few thousand years ago, maybe they were all coppers and the other colours were rare, and for some reason there's been genetic shift. And if so, why?) Do the different colours have slightly different flowering times? (I suspect they do.) And what would be the ecological effect of changing the current proportions?


2 comments:

  1. And now we're down to only one "copper" Banksia menziesii, due to a bush remnant having been bulldozed ... but I'll keep looking ...

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  2. I just wanted to say, different colours do indeed attract different groups of animals. The same goes for flower odour. Over time, specific pollinators are geared towards specific colours within their visual colour spectrum (honey bees are highly attracted to violet and blue, from memory) - and as the relationship between insects, birds, mammals and Australian flora goes back thousands of years, we're really quite specialised.

    There's a bush remnant behind our cottage in Malvern Springs which will be bull-dozed soon, but I've been logging photos as often as possible to have something to remember it by.

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