Re: Eucalyptus polyanthemos


----- Original Message ----- From: <mtnstar@ocsnet.net>
To: <medit-plants@ucdavis.edu>
Sent: Monday, April 24, 2006 1:05 AM
Subject: Eucalyptus polyanthemos


Hello all,

I just purchased two Eucalyptus polyanthemos, silver dollar gum, and I have conflicting reports on just how tall it eventually gets.&nbsp; One says 30 to 40 feet and another says 60 feet - does anyone have experience growing this tree?&nbsp; I don't want to block my view of the mountain tops.&nbsp; Do any of you know if this tree will take to pruning on the top - I would like to use the foliage in floral arrangements - and I thought I might be able to keep it in bounds this way?&nbsp; Thank you.
(You have an odd repetition in this e-mail of the meaningless combination of letters "&nbsp" which occurs at intervals for no apparent reason)

The NZ edition of Botanica gives ultimate size of this species as 80 feet! I have certainly seen some very tall upright trees of E polyantmanthemos, but in most cases the owners have got cold feet and removed them before they got anywhere as high as this, presumably fearing they might fall on their houses. Like many gums they are typically fast growing.

I do have experience of one which has grown rather differently which I planted in a local church property about 40 years ago. This was actually a poor specimen I got out of a bargain bin at tle local garden centre and had a distinctly weak stem. Presumably as a result of this, the tree has not gone up all that high. It is still probably no more than 30 feet tall, but instead it has spread enormously and though to some extent confined by a bit of shortening back of the main branches from time to time has ended probably rather wider than it is high. This has given it a very sturdy and stable form, but it certainly takes up a spectacular area and has actually been used occasionally as a sort of informal marquee for summer gatherings..

Any regular shortening back of the leaders on your trees could perhaps produce a similar effect??

Controlling the ultimate height of a tree without shortening its life can be very difficult, but regular "nibbling" of the top growth should have good chance of success I think. This is after all very similar to the natural pruning often seen in trees exposed to regular strong coastal winds. What really does damage is to suddenly shorten back a large upright trunk (most often with no reference to growth buds or surviving branches) so that a major wound is left without even a proper sap supply to help it heal. It is not surprising of so many sad trees treated this way do not survive long. One of our local arborists who has a horror of such mutiation has coined the term "Arbor decapitata" for trees treated this way.

I see a note in Botanica that this species is known in nature to grow sometimes on very poor shallow soils where it takes on a dwarf form with a twisted trunk. This would I guess result in effect in a natural Bonsai! It would evidntly pay at least not to give your trees any extra feed if you want to keep them down somewhat.

A method is sometimes used in Britain, and maybe elswhere, of growing trees solely for ornamental foliage for floristry or as bedding plants in large schemes by a drastic form of coppicing.The trunk is cut off quite close to the ground so it grows as a mass of juvernile foliage maybe three or four feet tall. This is in turn pruned regularly so the effect can artificially maintained. It can only be used of course for species which will easily regrow from just a stump.

This can look quite good, but the other method of keeping trees to a controlled height used in both Britain and some other Western European countries is pollarding which his rather similar. the tree being cut back to a trunk around 10-15 feet high with a mass of stubs every winter so it grows a new crown each spring. It has been traditionally used in London (though I don't know about recent years) to confine very big trees like Planes to a manageable size for street use, but in my view is hideous, especually after the trees have had ther annula winter decapitation. It was also introduce into some towns here by incoming European settlers, but I am please to see it is gradually dying out with many of the trees having being allowed to grow our (Or better still replaced with new and un-mutilated specimens).

Moira
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