Girdled branches

[David Humphries]

Have been watching this branch on this copper beech, on & off for the last few years.

 

Not showing any signs of shutting down apart from one of the upper side order branchlets out at the canopy periphery.

 

Its not grafted.

 

The cambial callus below & above the wound is now pretty much dysfunctional, the phloem is non existent but the xylem vessels within this diffuse porous wood are obviously still functioning.

Leaves are the same size & colour as the leaves on the other internal (non girdled) branches.

 

Pretty amazing, these trees

 

 

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[treeseer]

Amazing, indeed!

How can one tell the phloem is totally nonexistent? ok, the whole surface appears to be inactive xylem.

Even with cambium gone, other parenchyma cells are probably still functioning, and connected. That's a wild guess based on dissecting branches and firewood.

Parenchyma and phloem are hard for me to tell apart, in sight or in concept. Maybe it's that generally phloem transports matter and parenchyma transports energy?

[David Humphries]

Amazing, indeed!

How can one tell the phloem is totally nonexistent? ok, the whole surface appears to be inactive xylem.

Even with cambium gone, other parenchyma cells are probably still functioning, and connected. That's a wild guess based on dissecting branches and firewood.

Parenchyma and phloem are hard for me to tell apart, in sight or in concept. Maybe it's that generally phloem transports matter and parenchyma transports energy?

 

 

Phloem cells are the transporters of sugars etc, are they not ?

 

They're at the back of the (bark) cortex & as such are non exitent in this branch where there is no bark at the point that the wood is exposed.

 

I understand (through the medium of having just re-read the good doctor) that parenchyma cells are found radialy (rings) & axially (rays) throughout the wood & have the ability (along with cambial cells) to become callus material at the site of wounding.

 

 

 

 

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[treeseer]

ha thats a good medium all right. so the branch functions without sugars flowing in tubes through that bare patch. so evidently there is enough metabolism etc going on distal to the bare patch that needs for growth are met, with water coming up the xylem.

 

i just wondered since chemicals pass through parenchyma to effect signals, might some of those chemicals be part of metabolism proximal to the bare patch?

or does any of this matter?