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  1. #1
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    Default Nature of Ebony Wood - Heartwood Formation

    Nature of Ebony Wood - Heartwood Formation

    My suggestion recently that another dark wood may have been an ebony (What is this timber) provides me an opportunity to elaborate, and share some pics of an Australian ebony with interesting features referred to as "Phytoallexin* induced heartwood formation”. I better explain lest you roll your eyes and seek solace elsewhere.

    This effect is not peculiar to the ebonies but happens in MANY genera and species. The effects and causes are often species specific and the results (odours, colours produced and their appearance and location etc) are also species specific. Its evident in some spalted woods but also in ebony heartwood formation, shown below.

    This ebony example, a species called small leaf ebony, (Diospyros humilis) is a small Australian tree, from the dry scrubs of northern Australia, has a black scaly bark. Its orange fruit (about 4-5 mm in diam) look just like mini persimmons, which of course they are related to! However, even a large diameter tree, say 60 cm in diam., will often only have a small black heartwood. Smaller damaged trees will often have much more heartwood. Sadly the heartwood is very fractile, easily splitting and breaking. It has a pale sapwood and pink intermediate woood and black heartwood (sometimes striped with paler bands). The genus Diospyros was once called Maba.

    Other Diospyros species (most Australian, and many from overseas) show the same, small or no heartwood or sometimes a curiously dispersed heartwood, In parts of the world heartwood formation is induced deliberately by damaging the cambium (beating the stem) or naturally if and when fungal or other infection occur through tree damage.

    Some examples below are chosen to illustrate this peculiar response of plants to external challenges, a response which we love to see in wood while working on projects
    Euge

    PS: This has been published in 'World of Wood' the bimonthly journal of the International Wood Collectors Society

    *
    Phytoalexins are (usually) antimicrobial substances produced by plants in response to infection by a pathogen or elicitation by abiotic agents eg toxic elements mercuric salts. Even sweet potato slices infected with some fungi or treated with a mercury salt (an elicitor or stimuant) will produce toxic metabolites (certain terpenes), possibly to protect themselves or slow growth of the invading organism.

    SL EBONY.jpg
    Above : small diam log 10-12 cm dia, with bark and no end coating, Showing islets of induced heartwood between sapwood and intermediate wood pluse well formed black heartwood

    SL ebony 2.jpg

    Above: Larger Log of 20-25 cm dia (end-coated with a lacquer) with small heartwood but islets of black induced heartwood in sapwood and intermediate wood

    ebony branch .jpg Ebony other.jpg

    Above: Broken branch inside break (left) and outside (right) of same piece of wood showing where and how the heartwood formed from wound.
    Last edited by Euge; 12th Aug 2019 at 01:18 AM. Reason: to add explanation

  2. #2
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    So if your growing your own, and can wait the 80 or so years to get to a decent size, break a few branches off early or drill a hole at a fork
    Neil
    ____________________________________________
    Every day presents an opportunity to learn something new

  3. #3
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    Quote Originally Posted by dai sensei View Post
    So if your growing your own, and can wait the 80 or so years to get to a decent size, break a few branches off early or drill a hole at a fork
    Haha ... my life is almost over so don't have time to spare watching, poking, breaking / beating ebony trees and ...waiting. But I do recall looking for my first ebony tree in central Qld when visiting a friend. Came across a likely tree (i did my homework) with small round leaves and black blocky bark ... "that's interesting" I said to myself and as I usually do I look for a recently broken or dead one I can break off to look and smell the wood. The small 30-50 mm dia dead branch which I broke off was pure black (no sapwood) and had the distinct odour of ebony (I can always recognise it) and the black heartwoods all smell the same (to me anyway). I still have that piece as memorabilia

    Now to the purpose of this post...

    Here is a another larger ebony (Diospyros pentamera) a relatively common rainforest tree in the Ebony growing from near Batemans Bay NSW to the Atherton Tableland in Nth Qld Commonly called Myrtle Ebony, Black Myrtle and Grey Persimmon. This is what the wood look like of a log that was about 20-25 cm diam. It shows the odd spot of black ... and have never seen a black heartwood. The wood often shows spalting line, visible below.

    Diosp penta.jpg

  4. #4
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    Quote Originally Posted by dai sensei View Post
    So if your growing your own, and can wait the 80 or so years to get to a decent size, break a few branches off early or drill a hole at a fork
    Hey I recall gathering some fruit and seeds of the D humilis on another occasion (the small orange red 3-4 mm mini persimmons) and gave them (some time later) to the illustrious KJ (who you know and lows growing rare and unusual trees) to try and germinate them. I wonder if he ever did? It was a waste of time trying to germinate them in Gippsland Vic as our chilly climate is not amenable to this sub tropical species. However Diospyros kaki (Japanese persimmon) does grow well in
    here and the fruit are delicious and so much bigger!

    Euge

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