Tuesday, December 16, 2014

Gum Trees

Not always welcomed around the world, but one of Australia's most successful export is the humble gum tree, or Eucalyptus. "Look R", I nudged him, "Out the window, it is a forest of gum trees", and so it was, in Vietnam viewed from our train.


Gum trees are the most wonderfully evolved species to suit our climate. From the swamp gums which like to have wet feet, to gums that survive in some of the driest of our land, to gums that can withstand intense bush fires and recover. They form hollows in the trunks where branches break off to provide nesting sites for birds and animals, but only when they become quite old. Note politicians, stop the felling old growth native forests.

I could talk about how they breed and grow, but instead I will point out something about their leaves and bark, which are just so well designed.

Now here is a small gum tree branch with the leaves. The first thing to note is how they all hang down. If they were more conventional when rain hits them much of the water would bounce off and some stay on the leaf to quickly evaporate. But with the leaves pointing down and being the shape they are, every drop of precious moisture from rain or even dew is directed straight down to the ground to be taken up by the tree's roots, so necessary for their survival on the driest continent on earth.



The gum trees must also be able to survive fire and generally they can. Only the hottest bush fires seem to kill them. How do they survive?

Many gum trees have a thick fibrous bark and some have smooth bark that peels off in long sections and just hangs. Along comes the fire and the hairy bark quickly takes the fire up to the top of the tree as does the long pieces of very dry hanging bark of the smooth barked gum. Once the fire reaches the leaves, rich in eucalyptus oil and giving off strong fumes, they quickly burn and because of their long and hanging shape, the fire quickly reaches the top of the tree and away from the trunk of the tree. The end result is a tree with no leaves and burnt branches, but the trunk of the tree has been protected. From the trunk, new growth will quickly appear. Note, in the Australian state of New South Wales not far from Sydney are the well known Blue Mountains, so called because of the blue haze that hangs over them, which is eucalyptus fumes from the trees.

Photo from helsieshappenings of a Eucalypt with a thick and protective fibrous bark.


Photo from Clareges.blogspot.com of a smooth barked Eucaplypt with long tendrils of dry bark shed at the right time of the year for bushfires.


And just when I haven't seen anything at shorpy.com lately to point out to you, how is this photo from 1910 of Mount Tamalpais in Marin County, California. Our gum trees certainly began their journeys around the world very early.

28 comments:

  1. I love the look and atmosphere created by gums - have done so right from the first moment I put a foot on Australian soil. My mother used to think I was crackers but I just said it was a tree that spoke to me in a way that no european one had done so
    California was the first place we noticed gums out of what we always thought was their home environment. And I think the blue haze is the reason The Dandenongs are sometimes referred to by a similar name 'The Blue Dandenongs'
    Cathy
    (looks like I'll have to comment via blogger for the time being Andrew)

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    1. Cathy, they do have a lot of character. Yes, I had forgotten but I do remember the Dandenongs being called The Blue Dandenongs.

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  2. The scent of a eucalypt spells home to me - and I have been amazed at just how many places have eucalypts now...

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    1. EC, you will become very confused then if you are overseas and smell eucalypts.

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  3. Andrew, it is very interesting post about these trees. I have known so little about them so thanks for sharing. They are fantastic and they can survive sevee conditions like fire amazing..

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    1. Gosia, they are an amazing tree. There is one called the snow gum that grows in a very cold climate with snow in winter.

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  4. I am not into nationalist sentiment, and I dislike flag flying and sabre rattling. But the first time I saw gum trees all over Israel, I burst into tears. The Israeli climate is tough... Lots of other trees would not survive like our hardy Australian gum.

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    1. Hels, that is so sweet. Yes, they are good in many dry areas, including Africa, but are sometimes thought of as a pest.

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  5. the areas of Greece and Californian eucalypts have wildfires just like ours. That eucy oil sure burns well. I love the aroma of gums on a benign hot day, and the aroma in new rain. If I was far away from home and smelled gumtrees I would get teary as Hels did.

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    1. And don't forget Ann, eucy oil is great for removing sticky label residue and properly cleaning white boards.

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  6. I enjoyed that information which was well put together. Isn't nature wonderful!

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    1. WA, I started it ages ago and finished in a last minute rush. Could have been better, but thanks.

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  7. I remember as we lad (going back to the 70's) working for the Forestry Commission Nursery here in NSW collecting all the various eucalyptus seeds from around the state and sending them to various countries - especially California and Vietnam for reafforestation works. It was quiet successful.

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    1. Interesting Allan. Maybe the jury is still out on whether they are appropriate trees for such places.

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  8. They are a welcoming sight when returning from overseas.

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    1. Diane, I wonder if sniffing eucalyptus oil could be a cure for jet lag. It certain wouldn't be bad.

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  9. Eucalyptus are hugely popular and common in much of California. I love them (although they're always sharing something that makes my allergies rage). In San Diego County, groves of eucalyptus (6 million seeds from Australia) were planted in the late 1800s by the Santa Fe Railway because they thought the wood was perfect for railroad ties. When the wood turned out to be too soft, they simply turned the land into residential estate parcels.

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    1. How interesting Mitchell. Red gum timber has long been used here for railway sleepers, although we mostly use concrete now. The Stanta Fe railway just chose the wrong species. Red gum is a slow growing tree and the timber is as hard as a rock and lasts forever and burns hot but slowly like coal.

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  10. It seems to be a paradise for Pandas !!

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    1. Gattina, if they are in a zoo. Perhaps you mean as River points out, koalas. They eat quite specific gum trees and are generally found in cooler areas than the gums that can cope with drought conditions.

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  11. @Gattina; pandas eat Bamboo; it's koalas that eat eucalypts.

    The one thing wrong with gum trees is their tendency to suddenly drop a branch. Out in the bush it doesn't matter, but in a town you wouldn't want your car to be parked under it when a branch drops. Our Ford got a huge dent one year when a branch dropped and bounced off the bonnet.

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    1. River, as they are at times called, Widow Makers. It did matter out in the bush where the drover was asleep in a tent and a branch dropped. Interesting that you have personal experience of them.

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  12. I read somewhere that the eucalypt is the only genus represented from sea level to above the snow line! Cool, huh?!

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    1. You must have seen many Red. Interesting fact, if it is a fact. Do they grow in the far north, tropical climes?

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  13. I do like the Eucalypts Andrew, but they can look sgraggy too, I prefer the plane trees unfortunately I live in an area where the main tree species is the Eucalyt :)

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    1. I agree Grace. They are not trees for cities. There are a couple of smaller species that are ok for gardens though.

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  14. Yes it was amazing after the '83 fires how quickly the eucalypts regenerated. I have photos somewhere!

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    1. Not all though Fen. In some areas the heat was just so intense, it killed the trees, but hopefully their seeds sprouted.

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