I don't mean to stick my nose in where PhD's are contributing, but my
gardener's knowledge of botany leads me to note that if I recall correctly
the cambium layer is not engaged at all in the active transport of water or
nutrients. Water is transported from the root system (via root pressure,
changes in gradients, and transpirational pull) along the primary xylem. In
the root system, the cambium (or more properly, the vascular cambium) is
indeed a single cell-thick layer of cells from which arise the production of
primary xylem and primary phloem cells-- how a root gains girth. In the stem
tissue above the roots, there is vascular cambium and cork cambium (I have
heard vascular cambium referred to as intrafasicular cambium). These two
cambium layers work in synchrony to add girth to a trunk and lateral
branching. Vascular cambium lays down wood and inner bark, cork cambium
produces cork (bark).



David J. Bockman, Fairfax, VA (USDA Hardiness Zone 7)
Bunabayashi Bonsai On The World Wide Web: http://www.bunabayashi.com
email:


-----Original Message-----
From: Internet Bonsai Club ]On Behalf
Of Mark Hill
Sent: Thursday, July 17, 2003 12:32 PM
To:
Subject: [IBC] Dumb Cambium Layer Question


Thanks for this useful info Nina.

I always wondered how the cambium layer worked.

For example, If I only water a tree on one side, why don't the branches on
the opposite side of the tree die ?
I have trees in my garden that I know only receive water on one side, yet
the branches/leaves continue to grow all around the tree.
The cambium layer must be able to move water laterally as well as
vertically.

Interesting topic !!

Regards
Mark Hill - Harrisburg PA - Zone 6


-----Original Message-----
From: Internet Bonsai Club ] On
Behalf Of
Nina Shishkoff
Sent: Thursday, July 17, 2003 11:53 AM
To:
Subject: [IBC] Dumb Cambium Layer Question

Now you're getting the idea. Yes, there must be continuity from roots to
the
branch you're working on. If you cut two notches on the same branch, the
same rule applies.
Marty

Trees will compensate for things like that, given time. Both xylem
(water carrying elements) and phloem (nutrient-carrying elements) are
linked end-to-end with many seive-like pores. However, there are
lateral pores, too, and this allows lateral spread. The new growth
from the cambium the year after the cut will differentiate to
compensate as well. So you can make the two notches, but if the tree
experiences water stress, water will travel to other branches faster
than to that branch, weakening it. So make sure the tree is
well-watered until healing occurs.

The cambium is an awesome thing. We're used to thinking of organisms
with support on the outside (insects and crustaceans) or on the
inside (coral), but trees have both.
--
Nina Shishkoff

Frederick, MD

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************************************************** ******************************
++++Sponsored, in part, by Mike Page ++++
************************************************** ******************************
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+++++ Questions? Help? e-mail +++++