How tree branches are attached to trunks

[daltontrees]

Ha, Ha, I thought I replied to above an hour ago, but I must have mashed it up.

 

I don't see where the problem is. Consider a healthy stem and branch system, no cankers, burls, scars, etc. Topologically, the vascular cambium is a single, continuous layer of cells covering branch, stem, (and roots...).

Regulated by hormones in a manner not completely understood, the VC of the branch begins division earlier in the growing season than the VC of the stem. The orientation and differentiation of the daughter xylem cells is a function both of the orientation of the VC and of the cascades/pulses of those hormones. The annual ring of the branch completes formation followed by the annual ring of the stem. But throughout this process, the VC remains a single, continuous surface always to the outside of the derivative daughter cells.

OK, perhaps this will help: Visualize the lower surface of the angle formed by the stem and branch. Some portion of the VC surface will produce branch xylem early in the growing season and stem xylem later in the growing season. There is no "branch VC" getting covered by stem xylem. It's one, continuous surface. So does that make sense?

 

Your explanation is clear. I need to consider whether I agree with it. What holds me back immediately is that stem xylem is necessary (particularly in ringoorous trees) very early in the growing season for the water and nutrient supply for branch development.

[Fredward]

Everyone has probably seen this but a good video of Mattheck explaining some things about attachment.

 

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[daltontrees]

This is haunting me. See attached.

[daltontrees]

First one is Shigo model, relies on alternating growth of branch and stem wood, overlaying. Second is Mattheck as used in the video, relies only on branch wood having direct cambial connection to stem face.

 

I can't get the first to work in my mind.

[KTSmith]

Of course, both illustrations are static 2-D representations of 4-D processes. My quibble with the lower image from Prof. Mattheck is not the image but the labeling. The "bifurcated" stem wood is only bifurcated after adding a heavy mechanical stress. It is not at all bifurcated in the happy, healthy tree. The "branch tail" is the stemwood with the direct connecting flowpath into the branch. Calling it a branch tail is fine, I know what is meant, it's just stemwood. Perhaps we (including me) are trying to put to fine a point on these useful, but limited, cartoons.

[daltontrees]

I am leaning towards a hybrid of the two models that overcomes my problem with the Shigo model but looks more realistic than the Mattheck one. I have so many things on just now that I haven't the time to get the microtome out and make some thin sections. Spring would be best anyway, to try and catch a few growing sections.

[MWArb]

Found this.. thought you guys would like it

[woodchipperer]

On 08/01/2014 at 07:13, daltontrees said:

No, it was just generalised cynicism. Forget it, I am just a bit of a grump sometimes and the Slater article always came across to me as not particularly constructive.

I find this comment really interesting - and summing up of a generation of arborists I've encountered. Slater's article is about opening doors to more study - about recognising a vast number of studies and scientists work. It's about recognising the limitations of past thinking and moving forward.

 

I think it's one of the finest arb articles I've read in my 6 year career - and it's moved things on considerably. Matthecks publication of a model in 2013-2015, having apparently paid no attention to Slater's work further shows how important it was for someone like Slater to punch outside the box that everyone was trapped in.

 

Bloody good on him I say. Upset the apple cart to get the horse moving!

[daltontrees]

This debate was nearly a decade ago. Can you remind me pelase which Slater article you are talking about?