[neilep (OP)]

I have to say..I really luff trees !!

They are my all time favourite largest-plant-with-leaves-and-main-components-of-forest type things...

but check these barks out !! (why's it called " bark" anyway?)

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see what they have in common ?...that's right ..they are smoother than my wifes custard !!....

They're all rough !!!....now why is that ?...I do know some trees are smooth but why are most rough ?

I did ask a dog and all it did was bark !!...(groan !!....really really sorry about that !)

[Karen W.]

Probably the weather rain wind elements heat and cold frezing etc. Maybe as a protection against critters or even the weather itself! Only a guess though!

[Andrew K Fletcher]

The tubular structure under the bark is continually being replaced by more tubular structures, taking place in the cambium, which provides the liquid solutions from which tubes form. Tubular structures are kept open due to positive internal pressure which prevents the tubes from collapsing, these tubes become the phloem. Eventually the tubes become lignified by the solutes that circulate within the sap making the tubes strong enough to withstand negative tension, these strengthened tubes become the xylem, so we have a conveyor belt of new tubes being produced just below the inner surface of the bark under positive pressure. Which inevitably causes the outer skin to expand. The bark is fairly robust and ridged in many species of tree so cracks open as pressure is increased on the inside of the bark, causing splits to appear on the outer surface of the bark. But the same lignification process is happening continually on the inside of the huge tube (Bark) which is in fact a large fibrous sleeve around all of the inner structure that is continually being strengthened and repaired, just like our own skin is repaired when damaged. However we are able to shed skin cells that become desiccated as circulation fails to reach them and they die off. Whereas the tree is less able to remove the dead cells so they remain in site. Generally the larger these trees get the deeper the cracks form in the bark.

There are trees that do exfoliate their bark. The paper bark birch and maples being a prime example.

 


 


http://forestry.about.com/library/tree/blpart_bark.htm

 

[Karen W.]

WOW That is way better then my guess! WAY COOL! Thanks Andrew! That is very cool I have never heard of that.. especially the part about the tubular structures inside that keep multiplying.. the pressure part makes more sense with the deep cracking in the bark! Very nice information!

[neilep (OP)]

AWESOME ANDREW !!


This guy knows about trees !!...treerific !!  *groan*

Thank you Andrew !

I always do appreciate the time and effort that people go to, to answer a question.....