Australian tree question(s)

cowbell

I'm looking for some impartial, local boy, expert advice. Advice I've received from the local nurseries usually seems to favor whatever species they're trying to sell.
Please advise on E. Papuana and E. Citriodora as landscape trees. Any information on growth habit, limb drop, leaf, seed litter, or wind related failure is appreciated.
I'm in Arizona. It's dry, usually less than 7" rain per year. It's hot, temps in July and August are usually 46-50 C. The soil is hard, clay and alkaline.

Thanks.

Eric Frei

PDF attached stating the papuana performed well in situ Arizona.

Desert town Alice Springs also recommends it here.

Alice Springs Town Council - Recommended Plant Database - Corymbia aparrerinja = Eucalyptus papuana

It appears to not like heavy clay soils though .... another prefered option could be ....

Eucalyptus microtheca & E coolibah could be a better option for heavy soil. They have some data on these already in Arizona and they perform well and are more suited to clay soils and alkalinity.



I dont think the Citriodora would be as good a choice. They naturally do not occur as far west here as the others.

Attached Files

Eucalyptus papuana.pdf (179.8 KB, 24 views)

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dov

E. Papuana factsheet here should grow ok. E. Citriodora factsheet here might suit your conditions a bit better.

What sort of landscaping effect are you looking for? How large do you want the tree to grow? Do you want a showy flowering gum or just beautiful bark and shape?

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Eric Frei

I doubt it, I wrote ...

From your link ....

This guy is talking about less than 150mm rain fall a year in an alkaline clay soil, I really doubt that citriodora is going to do well.

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cowbell

I'm not looking for any particular look, but I am partial to the white bark on these two species.
Really, I want something with a columnar growth habit, thick shade for the western exposure of my house, and reasonable levels of litter.
I've stayed away from Euc to date because they have a terrible reputation around here for being messy and fragile. Recently though, I've noticed some recent plantings along the freeway that are not what I am accustomed to seeing when I think of eucs. In particular there are some white barked eucs with two distinct growth habits. One has a compact, straight, columnar habit with dense foliage. The other looks more like something from Dr Suess, with long horizontal-ish branches and tufts of foliage on the ends of those branches, but no foliage close to the trunk.
The highway department calls them Ghost Gum. But I've heard that name applied to both of the species in my original post. I'm just trying to figure out what's what.

Eric Frei

Well citriodora isn't white trunked but more columnar than the others mentioned.

The straighter ones are Euc grandis, regnans .... I suppose there's many but generally not seen inland arid conditions.

Most dont have much foliage near the trunk, just on the tips.

I think your best shot is going to be to drive around and take pictures of what you are after, close ups too including leaf and caps.

The columnar habit may outgrow it's usefullness though.

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dov

Another trick is just do a google image search for 'eucalyptus' and go through the pages til you find something you like, then google which part of the land it comes from.

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glennak

What has a whiter trunk than citriodora? Though in Queensland maculata are called citriodora aren't they? Well I was told they were.
There is a continuous change from one to the other like most Euc species there is a continuum and species are picked by paths that botanists took.
grandis and regnans have a snow flakes chance in hell of surviving with 7" rain.
Easiest way to pic citriodora is to get a leaf chrunch it up and use nasel spectroscopy (smell it) if it smells like lemons then it's lemon scented gum C. citriodora.
C. citriodora vary a lot with stability. A woman did a Doctorate on limb drop on them. It is totaly dependant on genetics. She picked some areas where seed should not be collected because they fall to pieces and other areas where they are very stable trees. The main trouble is seed is sold by species and weight and it is far cheaper to pick seed off branches laying on the ground rather than from 30m in the air.
I have removed young citriodoras in a kindergarten because they had dropped several branches. There are two planted on a roundabout on the top of Swanson St Melbourne that may have been planted by Batman (designer of Melbourne not from Gotham) that have never dropped a branch. In Perth WA they have a bad reputation as they have an avenue that drops a limb or two this was probably due to a lazy Queenslander picking seed off broken branches on the ground.
Back to Question what Ekka said plant C. papuana; they grow on rocky outcrops in central Australia in low rain fall areas to New Guinea where it can be rather wet.

Eric Frei

They're not pure white like the other gums, generally mottled but can be quite salmon coloured when shedding.

Spotty gums, we got a few, what about ole Henryi ... don't forget many people also confuse Angophora's with them.

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cowbell

Why? If it's about height, I'd be OK with 75-100 feet. They won't be closer than 40 feet to the house, so the taller the better.

cowbell

You guys have been a wealth of information. Thanks.

So, forget for a minute that I asked about specific species. What are the best gums for my climate? I will provide supplemental water for establishment.

I've been operating under the assumption that the local nurseries would be selling species adapted to our climate. The local place with the largest variety is at Australian Native Landscapes - Plant List A-E. Maybe y'all could peruse that list and make suggestions with my criteria in mind.

glennak

cowbell perhaps if you tell us what you want the tree to do how tall spread for shade or for show. Dicksonia antarctica is one thing that would not be a good choice they grow in moist shaded gullies and get sunburnt in direct sun light.

dov

Dicksonia Antarctica? Treeferns? I don't get it... Also the main factor with Eucs sloughing limbs is moisture. The drier it is, the more likely Eucs are to slough limbs. Eucalyptus Regnens (Mountain Ash) might grow even with such low rainfall, but it will slough limbs and twigs etc like crazy.

All in all, the Ghost Gum could be your best bet. It'll give you a creamy architectural trunk look, but prob won't get as tall as you want.

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glennak

As cowbell said"I've been operating under the assumption that the local nurseries would be selling species adapted to our climate." I was saying Dicksonia Antarctica wasn't adapted to his climate and was in the list.
I thought sloughing was the sheding of dead tissue by animals. Anyway I have heard the theory that branch drop may be caused by lack of moisture but is there any evidence? Besides the crash of red gum branches on hot still nights stories.
Eucalyptus Regnans might grow with such low rainfall? About as likely as the Dicksonia Antarctica that grow under them.

cowbell

It sounds like any of citriodora, papuana, microtheca or coolabah (coolibah?) will grow well. They're all available here. Any one of these in particular that has denser foliage, or won't bury me with litter? Any to stay away from?

I've looked at pictures on the internet, it's hard to find an image that defines a species. I've come here because the people on this forum are in a position to have seen hundreds of these trees. I only have pictures and a few examples around town. Your first hand insight has been a great help.

Eric Frei

Yeah, go with those. The leaf litter is nominal, they're evergreens but do shed.

The bark shed is worse than the leaf litter though.

Establish a mulched sort of garden beneath with sparse plantings of other drought toleratant low growing species, tuft grasses, cycads, aloe etc .... even a prostrate banksia (banksia birthday candles at bottom of list) or ground cover grevillea would be good. You dont want to smother the area just plant a little here and there but keep away from the trunk by maybe 3m with stuff.

It will help capture the falling debris too.

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dov

I grew up in a Euc forest. Just trust me on this one...

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Eric Frei

Please tell the story, I'd like to hear it.

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glennak

And what sort of Eucs were in this forest? Did you chec moisture content of fallen branches compared with non-fallen branches? Or at least compare soil moisture levels? Or is there something else you base this on?

dov

Dry seasons vs. wet seasons. When the ground is hard and cracked and the weather is hot and rainfal very low, it's dry. Most idiots don't need any special equipment or readings to figure that one out. The more dry weather, the more branches die on the trees and later fall.

For a few extra clues, I need to sweep the roof more often in Summer than Winter and get more broken tiles from fallen branches after hotter, dryer summers.

It's amazing what a wonderful education you can give people in arboriculture or any other subject, but you just can't teach intelligence...

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glennak

As you say you just can't teach intelligence but try hard. What sort of Eucs (this means what species of tree are you talking about). It appears that you are talking about dead branches falling rather than branch drop (which is live branches falling) which several people have been trying to find out why. I would think that every tree in existence would die back during dry periods and then these dead bits fall off. It is not resticted to your Euc forest (you'll have to trust me on this one) maybe you should leave it for a while and have a look around.

Eric Frei

I was thinking SLD (sudden limb drop) too.

We have some info here.

Do Gums just drop branches? Sudden Limb Failure post 21 has a good PDF

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dov

Ye, live too, bu mainly the limbs die back on the tree. Euc. Regnens and Obliiqua. From observation, it seems that Eucs, instead of just dropping leaves when dry like most trees will, seem to cut off the supply to whole limbs. This has also been conventionally held wisdom for many years.

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glennak

Yes that does seem to be true. They also have the auto shedding technique where they physically shear off dead branches as the trunk above and below push on the branch at different levels.