Eucalyptus mannifera

Brittle Gum at Bruce Ridge

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Identification history

	Eucalyptus mannifera	2 Aug 2019	MichaelMulvaney
	Eucalyptus elliptica	2 Aug 2019	KumikoCallaway

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User's notes

We wondered if this tree has a sort of disease with many bumps on the trunk. The tree on the right might have same root underground when looking at the base of the trees.

4 comments

MichaelMulvaney wrote:

3 Aug 2019

Burls form on tree roots, trunks and branches as a result of the abnormal development of bud growth cells. They appear as wartlike lumpy growths, roundish in shape and covered in coarse bark. Burls contain twisted, compact wood that is tougher than the wood from the rest of the tree.
Opinions vary as to the causes of burls but most experts agree on several factors, the first being disease. Although burl formation has not yet been fully analysed it seems able to be attributed to several diseases caused by bacteria, fungi or viruses with mould infestations being held as the most common cause. Infections just below the tree bark seem to trigger these abnormal growths with the tree's cells continuing to grow at the same rate as the rest of the tree but in a drastically changed direction.

Environmental stress and physical trauma also contribute to burl formation. The former can include a response to injuries from fire or flood or to irritation from constant wind or water erosion. Physical trauma can include insect damage, wounds from animals or injuries from logging. In many cases it will be a combination of factors that will cause burl growth and basically anything that can injure a tree has the potential to cause it.
https://www.australianwoodwork.com.au/blogs/news/australian-eucalyptus-burls-what-exactly-is-a-burl

KumikoCallaway wrote:

3 Aug 2019

Thank you, Michael. It is great to learn new things.

By the way, when I suggested species as 'Brittle Gum', I only looked at the common name on the list and did not check the scientific name. I did not realise there was another Brittle Gum choice. Apparently I chose the wrong Brittle Gum on the list. I looked up Eucalyptus Elliptica and it seemed to be called 'Bendemeer white gum' as its common name. Do you call this species as Brittle Gum as well, as it is shown on the Canberra Nature Map species list?

MichaelMulvaney wrote:

3 Aug 2019

Yes it is known as brittle gum in the Canberra area

KumikoCallaway wrote:

3 Aug 2019

OK, thank you :)

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